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PHY  S  I  C  A  L 

GEOGRAPHY 


BY    JAMES     MONTEITH 

AUTHOR   OF    GEOGRAPHIES,    ATLASES,    M.APS,    EASY   LESSONS   IN   POPULAR    SCIENCE, 

AND    POPULAR    SCIENCE   READER 


NEW    YORK  •:•  CINCINNATI  •:•  CHICAGO 

AMERICAN     BOOK     COMPANY 


lOITEITI'S  HEff  PHYSICAL  GEOGBAPHY. 

— G^5 


PREFACE. 

THE  attention  of  Teachers  and  School  Officers  is  respectfully  called  to  the  following; 
special  features  of  this  book  : — 

Its  Easy  Style  and  the  Clearness  of  its  Statements  fit  it  for  use  not  only  in 
3rammar  Schools,  but  also  in  High  and  Normal  Schools. 

The  Illustrations,  executed  by  the  best  artists,  serve  not  only  to  embellish  the 
work,  but  to  impress  vividly  upon  the  mind  of  the  learner  the  leading  truths  in  this 
most  interesting  science. 

The  Text  contains  the  latest  discoveries  in  Physiography,  Meteorology,  Hydrog- 
raphy, Magnetism,  and  Vulcanology. 

The  Maps  and  Charts  have  been  compiled  from  original  sources,  and  from  the 
latest  official  maps  of  the  United  States  and  British  Governments. 

The  subject  of  Magnetism  contains  much  new  matter  never  before  published,  the 
material  having  been  obtained  from  the  records  of  the  United  States  Magnetic  Observa- 
tory by  the  courtesy  of  Professor  Marcus  Baker. 

The  chapter  on  Volcanoes  is  based  upon  the  researches  of  Professor  Judd,  the 
highest  authority  on  the  subject  of  Vulcanology. 

The  subject  of  Ocean  Currents  contains  the  latest  discoveries,  including  those 
made  by  Commander  Bartlett,  of  the  U.  S.  Steamer  Blake. 

The  chapter  on  Rivers  and  Drainage  contains  much  that  is  new  in  the  way  of 
Hydrography.  The  facts  and  figures  have  been  obtained  from  the  records  of  the  U.  S. 
Engineer  Corps. 

The  subject  of  Winds  is  based  upon  the  researches  of  Professor  Ferrel ;  that  of 
Storms,  upon  the  records  of  the  United  States  Weather  Bureau.  The  latter  subject  is  the 
most  complete  exposition  of  the  Law  of  Storms  that  has  yet  appeared  in  a  school 
text-book.  It  contain^  hew  ^n^'is&ipGrtant  principles. 

It  is  the  only.  Physical  .Geography  containing  Bird's-eye  Relief  Maps. 

AMERICAN  BOOK  COMPANY. 


Copyright.   188o.  Oy  JAMES  MONTEITH. 
v.  \ 


ON-TENTS'} 


OHAPTEB  PASS 

I. -THE   EARTH   IN    SPACE.     Its  Motions,  etc.    ---------  5 

II.— THE    CRUST   OF   THE    EARTH.     Its  Strata,  etc.        -------  11 

III.— THE    LAND    SURFACE    OF   THE    EARTH.     Its  Continents,  etc.    -                       -  2O 

IV.— MOUNTAINS,    PLATEAUS,    AND    PLAINS  29 

V.— ISLANDS.     Reefs,  Lagoons,  etc.      -  36 

VI.— MAGNETISM.     The  Mariner's  Compass  ;  Magnetic  Storms,  etc.  -  4O 

VII.— VOLCANOES  AND  VOLCANIC  FORCES.    Phenomena  of  Eruption  ;  Geysers,  etc.    44 

VIII.— EARTHQUAKES.     Their  Causes  and  Effects  51 

IX.— THE    WATER    OF    THE    ATMOSPHERE.     Its  Forms  and  Uses                                  -  56 

X.— THE   WATERS    OF   THE    CONTINENTS.      Springs  and  Lakes       -  62 

XI.— RIVERS   AND   DRAINAGE.     What  Rivers  are  and  what  they  do  68 

XII.— AVALANCHES,    GLACIERS,    AND   ICEBERGS.     Their  Formation  and  Powers.  75 

XIII.— OCEAN   WATERS.     Their  Extent,  Color,  Waves,  etc.                    _____  81 

XIV.— TIDES.     What' Causes  them  86 

XV.— OCEAN   CURRENTS.     Their  Formation  and  Influence        ------  90 

XVI.— THE   ATMOSPHERE.     Its  Properties,  Winds,  Calms,  etc.  96 

XVII.— STORMS,    CYCLONES,    AND   TORNADOES.     Their  Nature  and  Effects         -       -  102 

XVIII.— CLIMATE       -  109 

XIX.— THE    DISTRIBUTION   OF   LIFE      -       -       -.-       -       -       -       -       -       -       -       -119 

XX.— MINERALS                                                              -___------  130 

APPENDIX. 

RELIEF   MAPS.     RECORD   OF   RECENT   DISCOVERIES,  Etc.           -        -       -       -  136 

258154 


NEPTUNE 


THE     SOLAR     SYSTEM. 

ji   diagram  showing  the  paths   and   relative  size  of  the  various  members   of  the   Solar  System 
Ihe  space  included   within   this   Orbit     of  Jupiter     represents   the  proportionate  size  of  the   Sun, 


PHYSICAL    GEOGRAPHY. 


CHAPTER    I. 


THE    EA.RTH    IN    SPECIE. 


1.  Stars. — Those  bright,  twinkling  points  of 
light  that  we  see  in  the  sky  after  the  Sun  has 
gone  down,  are  huge  balls  of  matter. 

2.  All  of  them  are  very  far  away,  and  some 
are  so  distant  that  a  ray  of  light,  moving  186,000 
miles  every  second,  would  not  reach  the  earth  for 
many  years  after  starting  on  its  journey.1 

3.  Nearly  all  of  these  heavenly  bodies  are 
many  times  hotter  than  the  hottest  furnace-fire — 
so  hot,  indeed,  that  they  exist  either  as  molten 
matter  or  else  as  a  vapor.3 

4.  A  few  of  these  balls  of  matter  are  con- 
stantly changing  their  position  in  the  sky.     They 
no  longer  give  light  of  their  own,  but  we  see  them 
because  the  light  of  the  sun  falls  on  them,  and  is 
reflected  to  our  eves. 


The  Earth  in  Space. 


5.  They  are  called  planets  (from  a  Greek  word  meaning  wanderer),  and  they  are  for- 
ever whirling  round  and  round  the  Sun. 

6.  The  Earth  is  one  of  these  Planets. 

7.  Fixed  Stars. — The  Sun  gives  both  light  and  heat  to  the  family  of  planets  whirling . 
around  him.     The  other  bright  bodies  are  called  fixed  stars. 

8.  All  of  the  other  Fixed  Stars  are  suns,  and  there  are  many  reasons  for  believing  that 
each  has  a  family  of  worlds  or  planets  revolving  about  it. 

1  The  nearest  fixed  star,  excepting  the  Sun,  is  star  a  of  the  constellation  Centaurus.     Its  light  is  three  and  one  quarter 
years  in  reaching  the  Earth. 

2  Every  substance  exists  in  at  least  two  of  three  states — solid,  liquid,  or  vapor.     By  heating  iron  it  melts,  and  finally 
ooils,  giving  off  an  orange-brown  vapor  or  steain.     Water  may  be  easily  changed  to  ice  or  to  steam.     By  withdrawing  the 
heat,  and  at  the  same  time  applying  great  pressure,  the  air  we  breathe  has  been  liquefied. 


NEW    PHYSICAL     GEOGRAPHY. 


9.  Our  Sun  and  his  group  of  worlds  are  called  The  Solar  System. 

10.  The  Solar  System  is  composed  of  the  Sun,  eight  worlds  called  planets,  twenty 
or  more  satellites  or  moons,  and  about  240  smaller  planets  called  asteroids,  besides  comets 
and  meteors.1 

THE    SOLAR    SYSTEM. 


MEMBERS  OP  SYSTEM. 

DISTANCE  FROM 

SUN, 
IN  MILES. 

MOVES  AROUND  SUN 

ONCE  IN 

DIAMETER, 
IN  MILES. 

No.  OF 
MOONS. 

SUN 

860,000 

IHercury    

35  750  000 

88  days. 

2992 

0 

\^enus  

66  750  000 

224  days. 

7,660 

0 

Earth  

92  300  000 

ly. 

7,918 

1 

Mars  

141,000,000 

1.9  y. 

4211 

2 

Asteroids  

Jupiter  

480,000,000 

11.8  y. 

86,000 

5 

Saturn  

881,000,000 

29.5  y. 

70,500 

8 

Uranus  (u'ra-nus).  .    

1,771,000,000 

84  y. 

31,700 

4 

Neptune      

2  775  000,000 

164  8  y. 

34,500 

1 

11.  Between  Mars  and  Jupiter  are  about  240  small  planets,  called  asteroids.     They  are 
very  small,  none  exceeding  300  miles  in  diameter. 

12.  Since  the  year  1600,  more  than  200  comets  have  been  discovered. 

13.  A  few  comets  belong  to  the  Solar  system,  and  travel  around  the  Sun  very  much  aa 
the  planets  do.     Others  came  from  regions  in  space  of  which  we  have  no  knowledge,  and 
after  passing  partly  around  the  Sun,  went  off  into  space,  never  to  return. 

14.  Meteors  are  commonly  called  shooting  stars.     They  may  be  seen  on  almost  any 
clear  night,  darting  like  balls  of  fire  across  the  sky.2 

15.  The  planets  in  their  order  from  the  Sun,  are  named  as  follows  :  Mercury,  Venus, 
Earth,  Mars,  the  Asteroids,  Jupiter,  Saturn,  Uranus,  and  Neptune. 

16.  The  line  in  the  diagram  on  which  each  planet  is  situated  shows  its  path  around 
the  Sun. 

17.  All  of  the  planets  move  around  the  Sun  from  west  to  east. 

18.  Their  orbits  or  paths  are  ellipses,  the  Sun  being  at  one  focus  or  center. 

19.  Each  of  the  planets  turns  on  its  axis  from  west  to  east. 

1  The  velocity  of  meteors  is  about  forty  miles  per  second.  Moving  with  such  a  great  velocity,  when  meteors  strike 
the  Earth's  atmosphere,  the  great  heat  developed  not  only  melts,  but  vaporizes  all^  but  the  largest  ones.  Many  fall  to  the 
Earth  and  are  found.  Some  are  composed  chiefly  of  iron  and  nickel.  Others  are  of  the  nature  of  stone.  At  least  one  comet 
(Tempel's)  has  been  proved  to  consist  of  an  immense  swarm  of  meteors  moving  in  a  cluster  around  the  Sun. 

8  It  is  usual,  but  hardly  correct,  to  say  that  the  planets  revolve  about  the  Sun.  The  truth  is  that  all  of  the  members 
of  the  Solar  System  revolve  about  a  common  center  of  gravity. 


THE    EARTH    IN    SPACE. 


20.  The  Earth  and  each  planet  beyond  it  are  attended  by  one 
or  more  moons. 

21.  Each  moon  moves  around  its  planet  in  an  elliptical  path 
from  west  to  east. 

22.  So  far  as  known,  each  moon  turns  on  its  axis  from  west 
to  east. 

23.  The  Earth  and  probably  the  other  planets,  are  composed 
of   the  same  elements  that  are  found  in  the  Sun.1    Of   many 
meteors  that  have  been  analyzed,  none  has  been  found  which  con- 
tains elements  other  than  those  which  compose  the  Earth. 

24.  Thus  it  will  be  seen  that  the  planets,in  many  respects, resemble  one  another.2 

25.  They  differ  widely  in  their  physical  condition,  however.     Some  are  apparently  hot 
and  fluid,  while  others  are  cold  and  solid. 

26.  Jupiter  is  still  glowing  with  heat,  and  possibly  gives  a  faint  light  to  its  five  moons. 
It  is  enveloped  by  dense  clouds  forming  the  bands  or  zones,  which  are  seen  in  the  picture. 

27.  Saturn  is  surrounded  by  several  flat  rings, 
one  outside  of  another,  whirling  swiftly  around  as 
though  they  were  the  rims  of  immense  fiery  wheels. 
It  is  thought  that  Saturn  is  a  world  yet  in  the  process 
of   formation,   and    that  the  matter  composing   this 
planet  is  partly  fluid  and  partly  solid. 

28.  Mars  is  a  world  very  much  like  our  own.     Its 
surface  is  diversified  with  oceans,  seas,  bays,  conti- 
nents, islands,  and  peninsulas.     Through  a  good  tele- 
scope one  may  see  the  frozen  zones  of  ice  and  snow, 
one  at  the  north,  the  other  at  the  south  pole.     Its 

position,  with  respect  to  the  Sun,  is  such  that  the  temperate  zones  of  Mars  have  seasons 
like  ours. 

29.  The  Moon. — At  least  one  of  these  heavenly  bodies,  the  moon,  has  become  cold  from 
surface  to  center.     The  air  and  water,  if  ever  there  were  any,  have  disappeared.     Its  surface 
is  covered  with  immense  craters,  many  of  which  exceed  fifty  miles  in  diameter.     During  the 
hottest  part  of  the  moon's  day,  the  temperature  is  nearly  that  of  melting  lead  ;  at  night,  it  is 
thought  to  be  about  200°  below  zero. 

30.  The  Sun. — The  Sun  is  a  huge  mass  of  matter  more  than  1,250,000  times  greater  than 


Telescopic  View  of  Saturn. 


1  This  has  been  discovered  by  analyzing  the  light  of  the  Sun  with  the  spectroscope.     Sodium,  potassium,  iron,  nickel, 
hydrogen,  and  many  other  elements  have  been  discovered  in  the  Sun,  and  most  of  them  also  occur  in  several  fixed  stars. 

2  It  is  thought  by  many  students  of  nature,  that  all  of  the  matter  which  composes  the  solar  system  was  originally  in 
one  mass  of  vapor ;  that  this  matter  began  to  gather  around  a  center ;  that  a  rotation  around  this  center  was  acquired ; 
that  the  mass  of  revolving  vapor  grew  smaller  in  bulk  as  it  cooled  ;  that  finally,  the  rotation  became  so  rapid  that  portions  of 
the  mass  were  thrown  off;  that  these  portions,  collecting  in  globular  masses,  formed  the  planets  ;  and  that  the  planets,  by 
a  similar  process,  threw  off  still  smaller  portions,  which  became  moons.     Although  this  is  a  supposition  only,  yet  there  are 
many  facts  which  make  it  worthy  of  belief. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Telescopic  yiew  of  Moon. 


the  Earth.  The  spectroscope  shows  that  it  is 
composed  of  substances  similar  to  those  found 
in  the  Earth  and  the  other  planets. 

31.  These  substances,  however,  owing  to 
the  intense  heat,  are  at  the  surface,  in  a  gas- 
eous or  a  fluid  state. 

32.  With  a  powerful  telescope, jets  of  gas 
at  a  white  heat  may  be  seen  projected  to  a 

E  distance  of  even  200,000  miles.  The  velocity 
with  which  these  immense  columns  of  gas  are 
thrown  upward,  sometimes  exceeds  250  miles 
per  second. 

33.  Sometimes,  funnel-shaped,  black  spots 
are  seen  on  the  Sun's  surface.     These  spots 
have    exceeded    140,000  miles    in    diameter. 
They  are  usually  in  violent  agitation.     In- 
deed, the  whole  surface  of  the  Sun  appears  to 
be  a  tempestuous  sea  of  white-hot  metallic 
vapors,  and  seething,  molten  elements. 

34.  In  shape, the  Earth  is  a  slightly  flattened  sphere,  bulging  at  the  Equator.1    This 
has  been  shown  in  various  ways. 

35.  Ships  have  sailed  around  it.     The  Earth's  shadow  is  circular.     A  straight  line  sur- 
veyed at  the  surface  of  the  water  apparently  rises.     In  reality,  the  surface  of  the  Earth 
curves  away  from  the  line. 

36.  The  Dimensions  of  the  Earth  are 

as  follows  : — 

Diameter  at  the  poles,  7899.2  miles. 
Diameter  at  the  equator,  7925.6  miles. 
Circumference  at  the  equator,  24,899  miles. 
Surface,  197,000,000  square  miles. 
Volume,  260,000,000,000  cubic  miles. 

37.  The  Earth  weighs  about  five  times 
as  much  as  a  globe  of  water  of  the  same  size. 
Its  density,  therefore,  is  said  to  be  5.     At  the 
surface,  however,  the  density  is  only  about  2| ; 
that  is,  a  cubic  foot  of  matter  composing  the 
surface  is  only  2%  times  as  heavy  as  the  same 
bulk  of  water. 

38.  Hence  it  is  thought  that  either  the  matter  in  the  interior  of  the  earth  is  compressed, 
or  else  that  it  is  composed  of  metallic  substances. 


Sun  Spot.     The  size  of  the  Earth  is  shown  in  one  corner. 


i  In  mathematics,  such  a  solid  is  called  an  oblate  spheroid.  The  Earth  is  not  a  true  oblate  spheroid,  however,  as  recent 
Investigations  have  shown  that  there  is  also  a  slight  bulging  at  the  temperate  zones.  This  "  square-shouldered  "  appearane* 
10  also  noticeable  in  Saturn  and  Jupiter. 


THE  DEARTH    IN    SPACE. 


39.  The  pupil  who  studies 
the  rocks  that  compose  the  sur- 
face of  the  Earth  will  contin- 
ually find  fresh  proofs  that  the 
whole  Earth  was  once  at  a  glow- 
ing white  heat.1 

40.  Motions.  —  There  is 
nothing  at  rest  in  the  Universe. 
Suns,   moons,   and    planets  are 
constantly  whirling  about  their 
common  center,  and  all  are  at 
the    same    time    sweeping    on 
through  space.     The  stars,  too, 
are  in  swift  motion,  each  in  his 
own  path,  never  for  a  moment 
resting. 

41.  The  Earth  has  two 
motions.    First,  it  turns  on  its 
axis,   causing   day  and  night.8 

Second,  it   moves   rapidly   around  the  sun,  making  the  complete  journey  in  about  365J 
•days.3 

42.  When  nearest  the  Sun,  the 
Earth  is  said  to  be  in  perihelion ; 
when    farthest    from    the    Sun,   in 
aphelion. 

43.  The  Earth  reaches  its  peri- 
helion -about  January  1st   and  its 
aphelion,  six  months  later.     Its  mo- 
tion is  most    rapid  while  in  peri- 
helion. 

44.  The  axis  of  the  Earth  is  in- 
clined 23£  degrees  toward  the  eclip- 
tic, as  may  be  seen  in  the  diagram 
at  the  top  of  the  next  page. 


An  ellipse,  representing  a  distorted  view  of  the  Earth's  orbit.  E  is  the  Earth;  F  is  one 
focus  of  the  ellipse ;  the  Sun  is  at  the  other.  The  Earth  is  3,000,000  miles  nearer  the 
Sun  at  perihelion,  than  six  months  later. 


The  Succession  of  Day  and  Ni^ht.    The  lamp  represents  the  Sun  ;  the  apple,  the 
Earth  ;  the  needle  on  which  the  apple  turns  represents  the  Axis  of  the  Earth. 


1  Although  the  temperature  of  the  Earth's  interior  is  far  above  the  melting  point  of  the  most  refractory  substances, 
it  is  by  no  means  certain  that  it  is  in  a  "  fluid  "  condition.     On  the  contrary,  tlie  Earth,  with  respect  to  the  Sun's  attraction, 
Tsehaves  like  a  solid  body. 

2  The  time  required  by  the  Earth  to  make  a  complete  revolution  is  divided  for  convenience  into  twenty-four  hours. 
At  the  equator,  the  circumference  of  the  Earth  is  nearly  25,000  miles,  but  the  parallels  decrease  rapidly  in  length  as  they 
-approach  the  poles.     It  is  evident,  therefore,  that  the  velocity  diminishes  as  the  latitude  increases,  being  greatest  at  the 
equator. 

In  latitude  0°,  the  velocity  is  1,040  miles  per  hour ;  in  latitude  80",  896  miles  ;  in  latitude  50°,  665  miles;  in  latitude 
70°,  354  miles  ;  in  latitude  80°,  180  miles;  and  at  the  poles,  it  is  0. 

8  The  length  of  this  journey  around  the  sun  is  about  580,000,000  miles.  This  divided  by  365£  x  24  gives  a  quotient  of 
••about  66,000  miles,  the  Earth's  velocity  in  miles  per  hour.  The  velocity  in  one  second  is  nearly  19  miles. 

There  is  one  other  motion  of  the  Earth,  which,  in  great  lengths  of  time,  is  thought  to  modify  its  climate.  The  poles  of 
the  Earth  are  constantly  moving  around  in  a  circle,  in  the  same  manner  as  does  the  upper  pole  of  a  sleeping  top.  This  move- 
ment is  completed  in  27,000  years. 


10 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


The  Earth's  orbit  as  it  would  appear  if  viewed  on  a  level  with  the  Ecliptic,  or  plane  of  the  orbit. 

45.  From  the  illustration  on  the  preceding  page,  you  will  see  that  the  Earth  is  nearest 
the  Sun  during  the  winter  of  the  Northern  Hemisphere,  where  most  of  the  land  is  situated. 

46.  The  effect  of  this  is  not  only  to  temper  the  extreme  heat  of  summer,  but  also  to 
moderate  the  cold  of  winter  in  this  hemisphere. 

47.  In  respect  to  its  distance  from  the  Sun,  the  inclination  of  its  axis,  and  its  velocity, 
the  Earth  seems  better  adapted  than  any  other  planet  for  the  sustenance  of  life.1 


WHAT  HAS  BEEN  TAUGHT  IN  CHAPTER  L 


The  stars  are  great  masses  of  intensely  hot 
matter  many  million  miles  away. 

The  nearest  fixed  star  is  the  Sun. 

The  Sun  is  attended  by  eight  planets  and 
about  24:0  asteroids  that  are  continually  whirl- 
ing about  it. 

There  are  also  comets,  some  of  which  are  a 
part  of  the  solar  system,  and  innumerable  me- 
teors or  shooting  stars. 

Most  of  the  planets  have  cooled  and  no  longer 
give  any  light,  but  others  are  thought  to  be  still 
in  a  fluid  condition,  and  perhaps  to  emit  a  faint 
light. 

All  the  planets  are  like  the  Sun  in  shape,  and 
they  resemble  one  another  in  their  motions  and 
general  properties. 

All  but  two  of  them  are  attended  by  moons  or 
satellites,  having  form  and  motions  like  the 
planets  themselves. 


Most,  if  not  all  of  the  planets  are  surrounded 
by  an  atmospJiere. 

The  motions  of  each  planet  are  principally  a 
spinning  upon  Us  axis  and  a  whirling  around 
the  Sun. 

The  Earth  measures  about  25,OOO  miles  in 
circumference,  and  nearly  8,OOO  miles  in  di- 
ameter. Its  distance  from  the  Sun  is  nearly 
93,OOO,OOO  miles. 

It  spins  on  its  axis  about  365  times  while  it 
moves  around  the  Sun  once. 

The  first  of  these  is  the  cause  of  the  succes- 
sion of  day  and  night,  the  second  causes  the 
change  of  seasons.1 

In  its  journey  around  the  Sun,  the  Earth 
moves  at  the  rate  of  6(i,OOO  miles  per  hour. 

The  path  of  the  Earth  is  an  ellipse,  the  Sun 
being  at  one  of  its  foci  or  centers. 

TJie  Earth  is  about  3,OOO,OOO  miles  nearer 
the  Sun  in  winter  than  in  summer. 


1  We  shall  learn  in  chapters  following,  that  life-forms  have  played  an  important  part  in  the  history  of  the  world. 
Many  of  the  rocks  have  been  formed  through  their  agency;  the  present  aspect  of  the  Earth's  surface  is  largely  owing  to  the 
work  of  plant  and  animal  life.  We  need  go  only  a  few  miles,  either  above  or  below  the  Earth's  surface,  to  find  conditions  of 
cold  or  of  heat  that  would  at  once  be  fatal  to  any  form  of  life  with  which  we  are  acquainted.  Yet,  through  all  the  changes- 
and  convulsions  of  nature,  life-forms  have  not  only  held  their  place,  but  they  have  also  steadily  progressed  to  higher  and 
more  complex  stages.  s  The  change  of  seasons  is  caused  by  the  revolution  of  the  Earth  around  the  Sun,  together  with 

the  inclination  of  the  Earth's  axis  in  the  same  general  direction,  throughout  the  year. 


THE     CRUST    OF    THE    EARTH. 


CHAPTER     II. 

THE     CRUST     OF     THE     EARTH. 

1.  It  is  thought  that  the  Earth  was  once  a  seething,  molten  mass,  and  that  through  the- 
course  of  long  periods  of  time,  the  surface  gradually  cooled,  until  a  solid  crust  formed  on 
the  outside.1 

2.  The  thickness  of  the  cooled  crust  of  the  Earth  is  estimated  at  from  55  miles  to  250 
miles.     There  are  at  the  present  time,  however,  no  means  whereby  it  may  be  measured  witTa 
any  certainty. 

3.  Condition  of  Interior.— That  the  interior  of  the  Earth  is  intensely  hot,  there  i& 
little  or  no  doubt — a  fact  which  may  be  shown  by  several  phenomena. 

4.  First,  the  shape  of  the  Earth,  slightly  flattened  at  the  poles,  is  such  as  would  be 
produced  by  the  spinning  of  a  partly  fluid  bocly  on  its  axis. 

5.  Second,  active  volcanoes  are  found  in  all  parts  of  the  world.     These  throw  large 
quantities  of  melted  matter  from  their  craters. 

6.  Third,  in  sinking  deep  shafts  and  artesian  wells,  there  is  a  gradual  increase  of 
temperature,  averaging  1°  F.  for  about  53  feet.2 

7.  Fourth,  geysers  and  hot  springs  occur  at  various  latitudes  in  every  continent.    The- 
waters  of  these  springs  sink  deep  into  the  Earth  through  crevices  and  passages.    When  they 
return  to  the  surface,  these  waters  are  heated  nearly  or  quite  to  the  boiling  point.     Hence 
they  derive  their  heat  from  the  Earth's  interior.3 

8.  Formative  Processes. — The  student  who  studies  the  crust  of  the  Earth  will  readily 
believe  that  long  periods  of  time  have  elapsed  since  the  Earth  took  its  present  form. 

1  Whether  or  not  the  interior  of  the  Earth  is  in  a  fluid  condition,  is  as  yet  a  matter  of  speculation.     The  stronger 
evidence  certainly  leads  to  the  conclusion  that  the  Earth  is  solid,  or  else  plastic,  from  center  to  surface.    Many  mathematicians 
are  of  the  opinion  that  the  great  pressure  from  the  outside  towards  the  center — that  is,  the  enormous  weight  of  the  overlying 
crust — causes  the  heated  interior  to  retain  a  condition  of  rigid  solidity. 

2  This  increase  in  temperature  is  by  no  means  uniform,  but  varies  between  27  and  198  feet  per  degree.     The  rate  of 
increase  is  greater  in  mines  than  in  artesian  wells.     In  many  instances,  the  rate  of  increase  is  very  largely  due  to  the  heat 
resulting  from  chemical  decomposition.    For  instance,  in  the  deep  shafts  of  the  Nevada  silver  mines,  the  temperature,  on  the 
same  levels  of  different  mines,  varies  from  10°  to  60°.     Beyond  a  depth  of  2,000  feet,  the  average  rate  of  increase  is  1°  for 
every  165  feet. 

The  thickness  of  the  Earth's  crust  cannot  be  estimated  from  these  figures,  however,  as  the  melting  point  of  solids- 
varies  with  the  pressure — the  greater  the  pressure,  the  higher  the  melting  temperature.  Besides,  the  crust  of  the  Earth  has- 
never  been  penetrated  more  than  one  mile  in  depth,  and  it  cannot  be  told  whether  or  not  the  increase  of  temperature  is  the 
same  for  all  depths. 

8  In  many  instances,  however,  hot  springs  derive  their  heat  from  the  chemical  changes  going  on  among  the  rocks. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


The  parts  of  the  map  shown  in  white  represent  the  first  land  of  the  United  States. 
"The  pans  in  dark  shading  along  the  coasts  remained  under  water  until  a  more 

recent  period. 
The  dark  shading  inland  were  vast  tracts  of  marsh  and  woodland,  but  now  they  are 

the  great  coal  fields  of  this  country. 


9.  Nearly,  if  not  all,  of  the  dry 
land  has  been  again  and  again  cov- 
ered by  the  waters  of  the  sea,  and  we 
may  also  believe  that  what  is  now  the 
bed  of  the  ocean  has  been  more  than 
once  lifted  above  the  surface  of  the 
waters. 

10.  Plant    life    in   the  greatest 
luxuriance,   and    most    wonderful    in 
form  and  size,  has  covered  the  face  of 
Earth  and  has  been  overwhelmed  by 
the  waters. 

11.  Gigantic     animals     lived, 
multiplied,  and  perished.     Enormous 
reptiles  inhabited  the  immense  swamps 
and  morasses  which,  during  different 
periods,   covered    large  areas  of   the 
Earth's  surface.     These  perished,  and 
were  succeeded  by  other  forms  of  life, 
and  these,  in  turn,  passed  away,  leav- 
ing the   story  of  their  lives  printed 
upon  the  rocks. 


12.  Different  climates  succeeded  one  another.     Parts  of  the  Earth,  at  one  period 
covered  with  ferns,  palms,  and  other  tropical  plants,  were  afterwards  buried  under  the  ice 
and  snow  of  a  dreary  winter  that  for  centuries  chilled  the  Earth's  surface. 

13.  Immense  glaciers,  or  rivers  of  ice,  have  rounded  off  the  sharp  hilltops  and  moun- 
tain sides,  and  have  ploughed  deep  gorges  through  the  hardest  rock. 

14.  Earthquakes  and  upheavals  have  raised  large  surfaces  of  land  out  of  the  waters, 
and  in  other  places,  have  sunk  great  areas  until  the  sea  covered  them  many  fathoms  deep. 

15.  Volcanoes  and  fissures  have  poured  out  floods  of  lava  until  immense  areas  of  ter- 
ritory have  been  covered  to  a  great  depth.1 

16.  Running  waters  have  worn  their  way  through  these  sheets  of  lava  and  other 
rock,   cutting  channels,  sometimes  exceeding  a  mile  in  depth,  into    the    mountains  and 
plateaus. 

The  wind,  blowing  loose  sand  and  dirt  day  after  day  and  year  after  year,  has  filled  up 
seas,  and  in  some  cases  has  severed  arms  of  the  sea  from  the  main  body  of  water.  Often  it 
has  extended  the  shore  for  miles  into  the  sea.2 

17.  These  changes,  carved  in  the  rocks  by  the  forces  of  nature,  have  been  going  on  for 
ages.     No  one  can  measure  the  time  in  years ;   it  can  be  measured  only  in  periods  of  un- 
inown  length. 

1  One  of  the  most  remarkable  lava  floods  is  that  of  the  northwestern  portion  of  the  United  States.  It  covers  an  area  of 
about  200,000  square  miles  in  Oregon  and  Washington.  This  sheet  of  lava,  where  the  Columbia  river  has  cut  through  it,  is 
nearly  4,000  feet  thick.—  Le  Conte. 

8  At  Pescadero,  California,  an  ancient  sea  beach,  has  been  found  two  and  a  half  miles  inland  from  the  present  shore. 
The  whole  intervening  area  has  been  filled  by  sand  driven  before  the  wind. 


THE     CRUST    OF    THE    EARTH. 


13 


18.  Bocks. — By  the  term  rock, 
is  meant  anything  that  enters  into 
the  structure  of  the  Earth's  crust. 
Sand,  clay,  gravel,  granite,  limestone 
and  slate  are  all  classed  as  rocks. 

19.  For  the  convenience  of  stu- 
dents, rocks  are  classified  in  several 
different  ways.     The  following  are 
the  most  commonly  mentioned  : 

Igneous       \  c   Aqueous 

or  >    and     <  or 

Unstratifiecl,  )  (.  Stratified. 

Fossiliferous, 
Metam  orphic, 
Primary,  Secondary,  Tertiary,  Etc. 

20.  Igneous  rocks    are  those 
which  have  been  formed  by  the  ac- 
tion of  heat.     They  are  usually  (ex- 
cept lavas)  found  in  dikes  or  irregular 
veins.   Frequently,  they  have  a  glassy 
lustre.    Lava,  pumice-stone  (volcanic 
froth),  and  trap-rock  are  examples. 
Igneous  rocks  are  unstratified.1 

21.  Aqueous 2  rocks  are  formed 
out  of  the  sediments  that  have  been 
deposited  by  water.  They  are  usually 


Igneous  Rocks.    Fingal'e  Cave. 


Work  of  Waves.    Fjord  in  Norway. 

soft,  and  have  a  clayey  appearance. 
Aqueous  rocks  are  always  stratified. 
Sandstones,  limestones,  claystones, 
and  slates  are  examples. 

22.    Stratified3   rocks    are    of 

aqueous  origin.  They  are  so  called 
because  they  appear  in  sheet-like 
masses  called  strata,  each  stratum 
having  a  uniform  thickness.  Strati- 
fied rocks  may  usually  be  split  into 
thin  sheets  or  layers.4 


1  The  teacher  should  procure  good  specimens 
of  each  rock  mentioned.  Typical  specimens  may 
be  purchased  for  a  small  sum  of  money.  In  many 
localities  they  may  be  found  in  large  quantities. 
In  mountainous  countries,  it  will  frequently  hap- 
pen that  all  the  rocks  here  described  may  be  found 
near  the  school  house. 


*  Aqueous,  from  the  Latin,  aqua,  water  ;  hence,  rocks  formed  by  the  action  of  water. 
1  Stratified,  from  the  Latin,  stratum,  a  layer  ;  hence,  rocks  arranged  in  layers. 

4  The  thin  layers  into  which  stratified  rock  may  sometimes  be  split  are  called  laminae.    Not  all  stratified  rock  is  capabl* 
of  being  thus  split  up. 


14  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 

23.  Slate,  soft  coal,  many  sandstones, 
and  shales  are  examples  of  stratified  rocks. 

24.  Unstratifled  rocks  do  not  occur  im 
layers.     They  are  rocks  of  igneous  origin.1 

25.  Aqueous    rocks    are    frequently 

Stratified  Rock.  „     .,          ,.  J 

called  sediments,  or  sedimentary  rocks. 

26.  The  fine  mud  which  running  water  often  contains  is  called  silt.     The  Missouri  and 
the  Sacramento  river  hold  in  suspension,large  quantities  of  silt. 

27.  Metamorphic 2  rocks  are  thought  to  be  sediments,  which,  under  great  pressure, 
have  been  changed  by  the  combined  action  of  heat  and  water,  until  they  resemble  igneous, 
rocks. 

28.  Metamorphic    rocks  are  generally  composed    of    crystals,   irregularly  cemented 
together.     Sometimes  they  appear  to  have  been  partly  melted.     Gneiss,   clay  slates,  and 
marble  are  examples.3 

29.  Fossiliferous  rocks  are  stratified  rocks  which  contain  the  casts  or  "petrified 
bodies  "  of  animals  or  of  vegetable  growths. 

30.  In  limestone?  the  stone  form  of  the  animal  or  plant  appears  as  though  it  had  been 
cast  in  a  mould. 

31.  In  sandstone,  however,  usually  the  print  or  impression  only,  is  found. 

32.  Among  these  imprints  and  casts,  are  found  the  tracks  of  reptiles  and  birds,  the 
stony  skeletons  of  huge  animals,  and  the  delicately  drawn  pictures  of  leaves  and  insects.4 

33.  Stratification. — Except  where  igneous  rock  has  been  thrust  to  the  surface,  the 
surface  of  the  continents  is  covered  with  sedimentary  or  aqueous  rocks. 

34.  The  various  strata  were,  at  first,  in  horizontal  layers  ;  but  on  account  of  the  con- 
traction of  the  Earth's  crust  in  cooling,  they  are  frequently  in  an  oblique  position.     Some- 
tunes  they  occur  in  folds,  and  often  they  are  greatly  crumpled  and  broken. 

1  "Beds  of  mud,  clay,  or  sand  may  often  be  traced,  by  insensible  gradations,  into  shales  and  sandstones.     In  many 

places,  the  process  of  consolidation  is  going  on  before  our  eyes Thus,  the  sediments  of  the  Rhine  are  now  consolidating; 

into  hard  stone,  and,  on  the  coast  of  Florida  and  Cuba,  comminuted  shell  and  corals  are  quickly  cemented  into  solid  rock." — 
La  Conte. 

Pupils  living  on  the  sea  shore,  may  sometimes  see  the  process  of  stratified  rock  making.  The  water  of  an  incoming 
tide  is  loaded  with  mud  and  ooze.  At  the  turning  of  the  tide,  the  mud  and  ooze  sink  to  the  bottom,  and  as  the  tide- 
slowly  recedes,  are  baked  and  hardened  by  the  sun.  The  next  incoming  tide  bears  a  fresh  deposit  of  mud,  which,  in  turn, 
hardens.  Shellfish  are  frequently  caught  between  layers,  and  birds  sometimes  run  over  the  fresh,  soft  surface.  Both  shellfish 
and  bird-tracks  are  covered  by  the  next  deposit  which  the  tide  bears.  Thus,  a  permanent  record  is  made,  which  may  be  read 
ages  hence. 

2  Metamorphic,  from  a  Greek  word  meaning  change  or  transformation. 

3  Granite  is  also  classed  among  metamorphic  rocks.    The  minerals  composing  granite  are  mica,  feldspar,  and  quartz. 
Whenever  granite  is  stratified  or  laminated,  it  is  called  gneiss.     If  the  feldspar  is  wanting,  it  is  mica  schist.    If  the  mica  is 
replaced  by  hornblende,  the  rock  is  then  called  syenite. 

Sandstone  is  composed  of  small  grains  of  sand  cemented  together  by  lime,  magnesia,  or  by  oxide  of  iron.  The  browo 
Btone  of  New  York  is  a  sandstone  of  the  latter  class.  Sandstones  are  frequently  metamorphic. 

4  These  casts  are  usually  called  "petrified"  remains  or  bodies.     The  substance  itself  does  not  turn  to  stone;  it  is 
gradually  absorbed,  and  the  cavity  is,  at  the  same  time,  filled  from  the  surrounding  rock. 


THE    CRUST    OF    THE    EARTH. 


16 


Strata  folded  by  Side  Pressure. 

strata  have  been  laid  bare  through  natural 

37.  It  is  in  this  way  that  the  book  of 
story  may  be  read  from  its  pages.   Each 
stratum  is  a  chapter  in  the  story  of  the 
world,  and  the  student  will  at  once  see 
why  we  begin  to  read  at  the  lowest. 

38.  It  is  not  always  easy  to  deter- 
mine the  relative  position  of  strata  at 
a  distance  from  each  other.     It  has 
taken  many  years  to  learn  the  little 
that  is  already  known. 

39.  Now,  the  position  of  strata 
can  generally  be  told  by  the  fossils 
contained  within  them,  and  the  differ- 
ent groups  of  strata  are  named  from 
the  character  of  the  fossil  plants  and 
annuals  they  contain. 

40.  Thus,  the  rock  lowest  in  rela- 
tive position  is  called  the  rock  of  the 
Azoic  (without  life)  era.1 

41.  Order  of  Strata. — Upon  this 
is  found  the  rocks  of  Palceozoic  (early 
life)  era.     Then  comes  the  Mesozoic 
(middle  life)  era.     Next  above  is  the 
Cenozoic  (new  life)  era.     Last  of  all  is 
the  era  in  which  man  appeared  on 
the  Earth. 

42.  On  page  16  the  pupil  will  see 
the  arrangement  of  the  various  ages 
as  they  occur.   Each  age  is  subdivided 
into  periods  and  epochs.2 

43.  Azoic  Life.  —  In  the  Azoic 
era,  no  forms  of  life  are  with  certainty 
known  to  exist.     It  is  thought,  how- 
ever, that  life  of  some  kind,  probably 
vegetable,  had  appeared  even  then. 


35.  In  some  localities,  where  strata  have 
been  tilted,  or  turned  with  their  edges  up- 
ward, fresh  layers  of  aqueous  rock  have  been 
deposited  on  the  upturned  edges  of  the  first. 
Strata  in  this  position  are  said  to  be  uncon- 
formable. 

36.  The  process  by  which  the  edges  of 
causes,  is  called  erosion. 

the  world's  history  has  been  opened  so  that  the 


Erosion. — Work  of  Rivers. 


1  Fossil  remains  have  recently  been  found  in  Azoic  rocks. 

5  The  series  of  strata  is  never  found  complete  in  anyone  place,  as  it  appears  in  the  table.  In  one  locality,  the  Azoic 
rocks  are  found  at  the  surface  ;  in  another,  secondary ;  in  still  another,  tertiary,  or  perhaps  secondary.  The  relative  position 
was  first  determined  by  noticing  the  overlapping  of  the  edges.  Now  the  geologist  can  determine  the  age  or  the  period  by 
the  character  ofthefossili. 


16 


MONTEITH'S     NEW    PHYSICAL     GEOGRAPHY. 


ERA. 


PSYCHOZOIC. 


CENOZOIC 
ERA. 


MESOZOIC 
ERA. 


O 

o 

N 
O 
Id 


cc 


QJ 


EOZOIC  OR 
AZOIC  ERA. 


AGE  OF  MAN. 


AGE  OF 

MAMMALS. 


AGE  OF 
REPTILES. 


CARBONIFEROUS: 

AGE  OF 
COAL  PLANTS 

AND 
AMPHIBIANS. 


DEVONIAN: 
AGE  OF 
FISHES. 


SILURIAN: 

.AGE  OF 
SHELL  FISH, 
SPONGES 

AND 
CORALS. 


FIRST  FORMS 
OF  LIFE. 


Order  of  Strata. 


Showing  rocks  of  different  periods  at  the  surface. 


44.  Palaeozoic  Life.  —  In  the  lower  strata  of 
the  Palaeozoic  era,  there  are  found  a  few  sponge- 
like  animals.     These  had  no  special  form,  and  were 
nothing  but  jelly-like  substances,  having  neither 
limbs,  head,  nor  digestive  organs. 

45.  Silurian  Life. — Above  these  strata  in  tbe 
Palaeozoic  time  are  found  the  rocks  of  the 

46.  Silurian  Age,  or  the  age  of  shell-fish.     Of 
these,  there  were  a  great  many  species. 


Fossil  Coral. 


47.  Corals,  sponges,  and  star  fish  were  abundant.    The  sponges  of  the  Silurian  age  were 
more  highly  developed  than  those  of  the  previous  time.     A  few  mosses  and  lichens  existed. 

48.  Devonian  Life. — The  Devonian   age  succeeded  the  Silurian.     This  is  the  age  of 
fishes,  during  which,  for  about  the  first  time,  an  animal  having  a  backbone  appears  on  the 
Earth. 

49.  Shell-fish  were  still  abundant,  and  they  were  also  of  a  higher  type.     Corals  were 
less  plentiful. 

50.  Land  plants  and  forest  trees  thrived,  and,  for  the  first  time,  insects  existed.     The 
Devonian  age  passed  almost  insensibly  into  the 

51.  Carboniferous  Age,  the  period  when  coal  plants  and  amphibious1  animals  began 
their  existence.    The  coal  plants,  which  included  horse-tails,  tree  ferns,  and  reeds  of  enormous 
size,  were  the  chief  feature  of  this  age. 


1  Amphibious  animals  are  those  that 'live  equally  well  either  on  land  or  in  water. 


THE     CRUST    OF    THE    EARTH. 


17 


Silurian  Shell-fish. 


Devonian  Fish. 


52.  These  plants  flourished,  died,  and  were  covered  by  the  sediments  of  successive 
floods,  till,  in  some  localities,  the  various  strata  of  coal  exceed  two  miles  in  thickness. 

53.  Reptiles  began  to  appear  during  this  age.     Fish,  shell-fish,  corals,  and  insects  also 
abounded. 

54.  The  climate  of  the  Carbonifer- 
ous age  was  moist  and  tropical. 

55.  Mesozoic  Life. — The  Mesozoic 
era  occurred  at  the  close  of  the  Carbon- 
iferous age. 


56.  Enormous   lizard-like  rep- 
tiles,  crocodiles,  and  turtles  were  the 
principal  life-characteristics  of  this  era. 
A  few  pouched  animals  appeared  at  the 
close. 

57.  Birds,   for  the  first  time,  ap- 
peared.   A  few  species  of  these  are  re- 
markable for  their  having,   instead  of 
beaks,  jaws  set  with  socket  teeth. 

58.  Ceiiozoic  Life. — The  Cenozoic 
era,    which  followed,   is  the  period  in 
which  mammals1  were  the  ruling  type 

of  animals.     The  animals  of  this  era  appeared  on  the  Earth  with  apparent  suddenness,  and 
in  great  numbers. 

59.  In  the  Bad  Lands,   the   plains  of   Colorado,  and  other  great  burial  grounds  of 
animal  remains,  are  found  the  fossil  bones  of  the  elephant,  the  rhinoceros,  the  horse,  the 
wolf,  the  deer,  and  many  other  kinds. 


The  Coal  Seama  of  the  Carboniferous  Age. 


1  Mammals — animals  which  suckle  their  young. 


18 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Fern  Leaf  of  Carboniferous  Age. 


60.  Before  the  dawn  of  this  era, 
all  of  the  species  of  gigantic  reptiles 
had  perished.     They  were  replaced  by 
smaller  species  of  crocodiles,  turtles, 
snakes,  and  frogs. 

61.  Europe  and  North  America, 

at  this  time,  were  regions  of  perpetual 
summer.  A  profusion  of  tropical  plants 
flourished,  and  tropical  animals  in  mul- 
titudes lived  and  covered  the  Earth. 

62.  More  than  1,5OO  species  oif 
insects  have  been  found  in  the  rocks 
of  the  Cenozoic  era.    Ants,  bees,  wasps, 
and  butterflies  of  various   kinds  are 
found  in  great  numbers. 

63.  Glacial   Epoch.  —  About  the 
middle  of  this  era,  a  change  of  climate 
throughout  the  whole  northern  hemi 
sphere  occurred,  and  the  tropical  cli- 


mate that  had  lasted  so  many  ages,  gave  place  to  one  of  icy  coldness. 

64.  Thus  was  ushered  in  the  great  Glacial  epoch.     During  this  epoch,  North  America 
and  Europe  were  scored  in  every  direction  by  glaciers  which  grated  over  the  surface  of  these 
continents. 

65.  The  sharp  tops  of  the  mountains 
were  rounded  off,  canons  and  ravines  were 
cut  deep  into  the  rocks,  and  the  plains  were 
covered    to  a  great    depth    by  loose  drift 
scraped  off  the  mountain  sides. 

60.  "With  the  coming  of  the  Glacial 
^epoch,  large  numbers  of  animal  species  dis- 
appeared from  the  face  of  the  Earth.  There 
survived,  however,  the  cave  bear,  the  cave 
lion,  the  horse,  the  reindeer,  and  the  wolf. 

67.  Age  of  Man. — At  last  appeared 
ihe  crowning  glory  of  the  history  of  cre- 
ation— Man.     With  his  coming,  the  reign  of 

brute  force  that  had  held  sway  so  many  ages,  ended. 

68.  In  the  bone  caverns  of  Belgium,  Germany,  and  Italy,  skeletons  of  human  beings 
are  found  with  the  bones  of  extinct  animals.     Scattered  about  the  cavern  are  rude  weapons 
and  implements  of  the  chase.     These  caverns  are  covered  up  with  limestone,  over  which  are 
gravel  and  drift  many  feet  deep.1 


Reptiles  of  Cenozoic  Era. 


1  In  England,  flint  implements  associated  with  the  broken  and  hacked  bones  of  extinct  animals,  are  found  above  the 
•Glacial  epoch,  and  under  the  gravel  beds  of  the  Champlain  epoch. 
*         "  Only  a  few  years  ago  an  almost  perfect  skeleton  of  a  Palaeolithic  man  was  found  in  a  cave  at  Mentone,  France.     It 


THE     CRUST    OF    THE    EARTH. 


19 


Age. 


Period. 


Epoch. 


CHAMPLAIN. 

FIRST  APPEARANCE  OF  MAN, 


69.  From  the  few  scraps  of  un- 
written history  which  he  has  left, 
primitive  man  seems  to  have  been  a 
savage  of  the  lowest  type.     He  lived 
in  caves,  and  eked  out  an  existence 
by  fishing  and  hunting.     He  neither 
cultivated  the   soil,  nor  did  he  have 
any  domestic  animals. 

70.  In  the  preceding  brief  history, 
the  student  will  not  fail  to  notice  that 
each  succeeding  age  has  brought  forth 

higher  and  better  developed  forms  of  life  than  tliose  of  a  preceding  period. 

71.  Improvement  and  progression  have  been  the  law  of  creation.     Each  succeeding 
chapter  of  the  story  sheds  a  greater  glory  upon  the  Great  Architect  of  the  Universe,  whose 
wisdom  and  power  know  neither  beginning  nor  ending. 


WHAT    HAS    BEEH    TAUGHT    IH    CHAPTER    II. 


The  Earth  was  once  a  molten  mass  of  matter, 
on  the  surface  of  which  a  solid  crust  formed. 

That  the  interior  of  the  Earth  is  yet  intensely 
hot. 

The  internal  heat  is  shown  by  volcanoes,  hot 
springs,  and  the  increase  of  temperature  towards 
the  center. 

That  various  forms  of  animal  and  plant  life 
have  appeared  and  disappeared. 

That  t/ie  whole  surface  of  the  Earth  has  been 
changed  btj  the  action  of  water,  and  also  by  vol- 
canic action. 

The  story  of  these  great  changes  has  been  re- 
corded in  the  rocks. 

Rocks  are  classified  as  stratified  or  aqueous, 
nnstratified  or  igneous,  melamorphic,  and  fos- 
siliferous. 

Stratified  or  aqueous  rocks  are  formed  by 
the  action  of  water;  they  occur  in  layers  or 
strata. 

Unstratified  or  igneous  rocks  are  formed  by 
the  fusion  of  the  substances  composing  the 
Earth. 


Metamorphic  rocks  are  aqueous  or  sediment- 
ary rocks,  changed  by  the  combined  action  of 
heat,  pressure,  'and  ^vater. 

Aqueous  rocks  generally,  and  metamorphic 
rocks  sometimes,  contain  the  casts  or  the  im- 
prints of  animals  and  plants. 

lit  the  lowest  rocks,  the  Azoic,  few  forms  of 
life  appear. 

In  the  Palaeozoic  era,  which  followed,  sponge- 
like  animals,  corals,  shell-fish,  and  fish  having 
backbones,  appeared  in  succession. 

In  the  latter  part  of  this  era,  huge  amphib- 
ians and  the  vegetation  ivhich  formed  most  of 
our  coal  fields,  thrived  in  great  abundance. 

Hie  Mesozoic  era,  which  followed,  is  noted 
for  tlie  great  number  of  gigantic  reptiles,  the 
prevailing  types  of  life  during  that  period. 

In  the  Cenozoic  era,  which  succeeded,  mam- 
mals were  the  prevailing  type  of  life. 

That  man  first  appeared  just  after  the  close 
of  this  era. 

Each  age  Juts  produced  higher  forms  of  life 
than  those  of  the  ages  preceding  it. 


is  that  of  a  well-formed  man  with  an  average  sized  skull,  and  a  facial  angle  of  85°.  The  antiquity  of  this  man  is  undoubted, 
for  his  bones  are  associated  with  those  of  the  cave  lion,  cave  bear,  rhinoceros,  and  reindeer,  together  with  tliose  of  living 
species.  The  bones  of  the  skeleton  are  all  in  place,  surrounded  with  the  implements  of  the  chase  (flint  implements)  and  the 
spoils  of  the  chase,  viz.,  the  bones  of  the  reindeer,  perforated  teeth  of  stag,  etc.  Of  the  latter,  22  lay  about  his  head.  These 
are  supposed  to  have  been  worn  as  a  chaplet.  This  Quaternary  man  seems  to  have  laid  himself  quietly  down  in  his 
house  and  died." — Le  Conte. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


THE 


CHAPTER     III. 
STTRFA.CE     OF     THE 


Comparative  Areas  of  Oceans,  Continents,  and  Islands. 


1.  Extent.  —  The    surface    of    the    Earth 
covers  an  area  of  about  197,000,000  square  miles. 
Of  this  area  144,000,000  are  water,  .and  the  re- 
maining 53,000,000  square  miles,  land. 

2.  The  land  surface  of  the  Earth  consists 
of  several  large  bodies  of  irregular  shape,  called 
continents,   together  with  a  large    number  of 
islands. 

3.  The  islands  have  an  aggregate  area  of 
3,000,000  square  miles. 

4.  Shape.  —  These  land  masses  have  each  a 
triangular  shape,  broad  at  the  north  and  tapering  to  a  point  at  the  south.    They  form  the  six 
continents. 

5.  Position.  —  The  largest  continents  are  crowded  about  the  North  Pole,  stretching 
southward  in  three  directions.     The  three  northern  lie  almost  wholly  in  the  North  Tem- 
perate, and  the  three  southern,  in  the  Torrid  zone. 

6.  Taking  the  north  of  France  as 
a  center,  a  great  circle  will  divide  the 
Earth  into  two  hemispheres,  the  north- 
ern one  of  which  contains  nearly  all 
the  land.     A  point  southeast  of  New 
Zealand  is  the  center  of  the  water  hemi- 
sphere. 

7.  The  land  surface  may  be  sepa- 
rated into  two  divisions,  which  lie  on 
opposite  sides  of  the  Earth.     For  con- 
venience, the  two  halves  of  the  Earth 
are  called  the  Eastern  and  the  Western 
Hemisphere. 

8.  The    Eastern     Hemisphere 

contains  the  continents  of  Europe, 
Asia,  Africa,  and  Australia,  together 
with  a  large  number  of  islands.  It  contains  nearly  two-thirds  of  the  entire  land  surface. 

9.  The  Western  Hemisphere  contains  the  continents  of  North  America  and  South 
America,  together  with  many  islands. 

10.  Coast  Lines.—  Of  the  six  continents,  the  northern  group  of  three  is  bounded  by  a 
very  irregular  coast  line.    This  irregular  coast  forms  a  great  number  of  bays,  gulfs,  and 
peninsulas. 


The  general  form  of  each  of  the  land  divisions  is  that  of  a  triangle,  the  apex 
pointing  toward  the  south. 


THE  LAND  SURFACE  OF  THE  EARTH. 


AUSTRALIA 

EUROPE 

S.  AMERICA 

N.  AMERICA 

AFRICA 

ASIA 

o 
o 
o 

o 

0 

o 

o 
o 
o 

o 

o 

0 

0 
0 

o 

0 

o 
o 

0 

0 

o 

c> 

0 

ix 

0 

0 

to 

0 
0 

<t 

0 

o 
o 

o 

0 
0 

w 

<•> 

10 

CO 

03 

K 

Relative  Size  of  the  Continents,  iu  Square  Miles. 


11,  Such  indented  coasts  are  of  the 

greatest  importance  to  the  people  inhabiting 
a  continent,  because  the  existence  of  a  large 
number  of  good  harbors,  more  than  any  other 
cause,  promotes  a  diffusion  of  industries, 
knowledge,  and  civilization.  They  also  mod- 
ify and  temper  the  climate  of  a  country,  in- 
creasing its  fertility  and  productiveness. 

12.  The  accompanying  table  shows  the 
relative  length  of  coast  to  continental  areas  : 


CONTINENTS. 

AREA. 

COAST 
LINE. 

SQ.  M.  FOR 

IM.OFC'ST. 

Asia  

17,000  000 

35,000 

500 

Africa  

12  000  000 

16000 

750 

North  America.  . 
South  America... 
Europe  

8,400,000 
6,500,000 
3  700  000 

22,800 
14,500 
19,500 

368 
449 
190 

Australia  

3  000  000 

10000 

300 

The  Distribution  of  Land  and  Water. 

13.  It  will  be  noticed  by  this  comparison  that  Europe  ranks  first,  and  Africa  last.     It 
might  truthfully  be  said  that  the  intellectual  and  commercial  importance  of  a  continent 
depends  directly  upon  the  comparative  length  of  its  coast  line. 

14.  Surface. — Continents  are  not  plain,  level  surfaces.    They  are  diversified  with  moun- 
tains and  valleys,  plains  and  rolling  hills,  table-lands  and  lake-beds,  rugged  hills,  ravines, 
and  winding  rivers. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


AREA 
17.000,000 
SQ.  MLS. 


Length  of  Coast  compared  with.  Area.     The  circumference  of  the  outer  circle  represents  the  length  of  the  coast  line. 

15.  Mountains  appear  in  ranges, -which  are  usually  of  great  length. 

16.  A  mountain  chain  or  system  consists  of  several  parallel  ranges.     Thus,  the  Alle- 
ghany,  the  Blue,  and  the  Cumberland  range  of  mountains,  together,  form  the  Appalachian, 
system. 

17.  The  principal  mountain  system  of  a  continent  is  generally  near  the  coast. 

18.  Plateaus  are  high  elevations  of  land  which  cover  large  areas.     Plateaus  of  small 
area,  having  level  tops,  are  called  table-lands. 

19.  Plains  are  low,  level  surfaces,  usually  having  an  extensive  area.1 

20.  The  arrangement  of  these  land  features  with  reference  to  one  another,  affects  not 
only  the  drainage  of  continents,  but  also  the  climate,  the  commercial  industries,  and  th& 
productions  of  the  soil.     Hence, the  surfaces  of  the  continents  must  be  carefully  studied. 

21.  Eastern  Hemisphere. — The  Eastern  Hemisphere  extends  from  Bering2  Strait,  on 
the  northeast,  to  Cape  Verd,on  the  southwest.     The  continents  of  Europe  and  Asia  form  one- 
united  body  of  land.     Africa  is  naturally  a  peninsula,  joined  to  Asia. 

22.  Its  chief  system  of  mountains  and  highlands  extends  nearly  the  whole  distance 
from  the  northeast  to  the  southwest. 

23.  From  the  highest  parts  of  this  system,  the  surface  slopes  toward  the  surrounding 
waters.     The  northern  slope  is  gentle  ;  the  southern,  abrupt. 

24.  Western  Hemisphere. — The  Western  Hemisphere  is  composed  of  two  triangular 
masses  of  land  joined  by  an  isthmus.     It  extends  nearly  north  and  south,  having  a  slight 
inclination  toward  the  northwest. 


1  By  common  consent,  land  surfaces  having  an  elevation  exceeding  1,500  or  2,000  feet  are  called  plateaus ;  those  having 
a  less  elevation  are  plains.     *  Bering,  or  Behring.     The  former  is  now  used  by  the  best  authorities. 


THE    LAND     SURFACE     OF    THE    EARTH. 


23 


A.  Mountain  Chain. — Highest  peak.— Volcano.— Table  land,  or  plateau.— Lakes  at  different  elevations. — Glacier,  ending  in  a  waterfall,  which,  with 

outlet  of  upper  lake,  forms  the  riven 

25.  The  mountain  system  of  the  Western  Hemisphere  extends  from  Bering   Strait 
to  Cape  Horn.     On  the  western  side,  the  slope  is  abrupt ;  on  the  eastern,  it  is  gradual,  being 
interrupted  by  low  ranges  of  mountains  near  the  Atlantic  ocean.1 

26.  Asia. — Asia  is  the  largest  of  the  six  continents.     The  Himalaya,  together  with 
several  parallel  ranges,  forms  the  great  mountain  system  and  the  main  axis  of  the  continent. 
Mt.  Everest,  whose  altitude  is  29,000  feet,  is  the  highest  point. 


SECTION  ON"  3O°    OIT  X.ATITT7DE-. 


Proflle  of  Asia. 

27.  The  great  plateaus  of  Asia  are  inclosed  by  these  mountains.    Arabia  and  western 
Hindostan  are  also  vast  plateaus. 

28.  The  plains  of  Asia  are  north  of  the  mountain  system.     They  slope  gently  toward 
the  Arctic  ocean.    There  are  smaller  plains  on  the  borders  of  the  Caspian  sea,  in  the  eastern 
part  of  China,  and  in  western  Hindostan. 

29.  Asia  is  drained  by  a  number  of  large  rivers  flowing  from  the  slopes  of  the  moun- 
tains into  the  surrounding  waters. 

30.  The  Caspian  sea,  the  sea  of  Aral,  and  the  basin  of  the  Dead  Sea  are  below  the 
ocean  level. 

31.  Six  large  peninsulas  on  the  eastern  and  the  southern  side  are  formed  by  moun- 
tain ranges  and  plateaus  extending  into  ocean  waters. 

1  In  the  capitalization  of  proper  names,  the  plan  followed  is  the  same  as  that  of  The  American  Cyclopedia. 


24 


MONTEITff'S    NEW    PHYSICAL     GEOGRAPHY. 


32.  Several  chains  of  islands,  formed  by  partly  submerged  mountain  ranges,  lie  near 
the  eastern  and  southeastern  shores  of  the  continent. 

33.  Europe. — Europe  joins  Asia,  the  Ural  mountains  being  the  natural  boundary. 

34.  The  mountain  systems  of  Europe  partly  inclose  the  continent.     The  chief  of 
these  are  the  Scandinavian,  Ural,  and  Alpine  chains,  the  last  system  being  the  principal 
system. 


Profile  of  Europe. 

35.  From  this  system,  the  Austrian  Alps  and  the  Pindus  extend  into  the  Mediterranean 
sea.  forming  the  peninsula  of  Turkey  and  Greece.    The  Apennine  mountains,  in  a  like  manner, 
form  the  peninsula  of  Italy;  and  the  Scandinavian  mountains,  the  peninsula  of  Norway  and 
Sweden. 

36.  The  highest  point  in  the  Alps  is  Mt.  Blanc,  15,800  feet  high.     Mt.  Elboorz,  in  the 
Caucasus   (cau'ca-sus)  mountains,  has  an  altitude  of  17,000  feet. 

37.  The  largest  plateau  is  the  Spanish  or  Iberian  peninsula.     Central  and  southern 
Europe  consists  almost  wholly  of  plateaus  traversed  by  river  valleys. 

38.  The  plains  of  Europe  lie  in  the  northern  and  northeastern  part.    The  great  Russian 
plain  covers  about  one-half  of   Europe.     Northern  Germany,  the  Netherlands  (Holland), 
western  Prance,  and  a  part  of  Belgium  are  embraced  in  this  plain.1 

39.  Europe  is  drained  by  a  great  number  of  rivers  rising  in  one  or  another  of  the 
three  general  elevations.    Those  of  the  Russian  plain  rise  in  the  Valdai  Hills  or  on  the  slopes 
of  the  Ural  mountains.     The  others  rise  chiefly  in  the  Alpine  mountain  system,  or  else  in  the 
Scandinavian  mountains. 

40.  Africa. — Africa  is  an  immense  plateau,  taking  its  shape  from  the  mountains  and 
the  abrupt  slopes  that  form  its  coast. 

41.  The  chief  mountain  range  is  on  the  eastern  side  of  the  continent.    The  Kong 
mountains  form  the  western;  and  the  Atlas  mountains,  a  portion  of  the  northern  border.2 


-20,000 
-15,000 
-10,000 
-5,000 
SEA  LEVEL  ATLANTIC 


SECTION  ON  THE  EQUATORMT -KILIMANJARO 


Profile  of  Africa. 


1  A  portion  of  Holland  lies  below  the  sea  level,  and  is  protected  from  the  encroachment  of  the  sea  by  means  of  dikes. 

2  The  Crystal,  Cameroons,  and  Mocambe  ranges  are  a  continuation  of  the  Kong  mountains.     The  sharp  bend  of  this 
mountain  chain  forms  the  Gulf  of  Guinea, 


THE  LAND  SURFACE  OF  THE  EARTH. 


25 


42.  The  highest  points  of  land  are  Mts.  Kenia,  about  20,000  feet,  and  Kilima  Njaro, 
about  18,500  feet  in  height. 

43.  The  southern  half  of  the  African  plateau  has  an  average  elevation  of  5,000  feet ;  the 
northern  half,  about  1,500  feet. 

44.  Southeast  of  the  center  is  an  elevated  basin  over  6,000  feet  above  the  sea  level. 
This  basin  contains  several  large  lakes,  which  are  the  sources  of  the  great  river  systems 
of  the  continent.1 

45.  A  small  portion  of  the  Sahara,  south  cf  Tunis,  is  from  100  to  300  feet  below  the 
sea  level. 

46.  North  America. — North  America  is  an  immense  plain,  bordered  on  the  west  and 
southwest  by  the  bold  and  rugged  Rocky  mountain  system,  and  on  the   east  by  the  low 
parallel  ranges  which  constitute  the  Appalachian  system. 


Bird's-eye  View,  or  Relief  Map  of  a  part  of  North  America. 

47.  The  Rocky  mountains  are  the  main  axis  of  the  continent.     Parallel  to  these  is  a 
chain  of  mountain  ranges  consisting  of  the  Cascade,  the  Sierra  Nevada,  and  several  shorter 
ranges,  each  having  an  altitude  of  about  8,000  feet. 

48.  The  highest  points  are  Mt.  St.  Elias,  19,500  feet;  Mt.  Popocatepetl,  18,500  feet ;  and 
Mt.  Whitney,  15,086  feet.     There  are  forty  peaks,  each  over  10,000  feet  high,  in  this  system. 

49.  In  the  eastern  part  of  the  continent  is  the  Appalachian  system,  consisting  of  sev- 
eral low  parallel  ranges,  forming  an  angle  of  45°  with  the  main  axis. 

50.  The  great  plateaus  of  North  America  lie  between  the  parallel  ranges  of  the  Rocky 
mountain  system.     The  most  important  of  these  are  the  plateau  of  Mexico  and  the  Great 
Basin. 


1  The  Zambeze,  the  Livingstone,  and  the  Niger  have  cut  their  channels  through  deep  mountain-passes  in  order  to 
reach  the  sea. 


26 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Sierra  Nevada  Mt$. 


Wasatch  Mts. 
Bird's-eye  View  of  the  Great  Central  Basin. 


llocky  Mts. 


51.  The  Great  Central  Plain  lies  between  these  mountain  systems.     The  highest  part 
of  this  plain  is  called  the  Height  of  Land.     It  lies  near  the  northern  boundary  of  the  United 
States,  and  forms  one  of  the  principal  continental  watersheds.     Although  it  is  traversed  by 
low  ranges  of  hills,  it  is  neither  mountainous  nor  generally  rugged. 

52.  The  Great  Lakes,  situated 
at  the  summit  of  the  Height  of  Land, 
constitute  the   largest  body   of   fresh 
water  in  the  world.1  ^ 


Section  of  Mexico  from  the  Pacific  Ocean  to  the  Gulf  of  Mexico. 


53.  The  drainage  of  North  Amer- 
ica is  more  complete  than  that  of  any 

other  continent,  the  principal  drainage  areas  being  the  Arctic  slope,  the  Gulf  slope,  the  Great 
Basin,  the  Atlantic  slope,  and  the  Pacific  slope. 

54.  Several  remarkable  depressions  exist  in  the  Pacific  Highlands.     Death  Valley 
and  the  Sink  of  the  Mojave  (mo-hali've)  river  in  California,  are  the  principal  ones.     The 
former  is  about  420,  and  the  latter  350  feet  below  the  sea  level. 


Bird's-eye  View  of  a  part  of  South  America. 


1  The  summit  of  the  Height  of  Land  may  be  traced  by  drawing  a  line  on  the  map,  between  the  sources  of  the  tribu- 
taries of  the  Mississippi  and  the  sources  of  those  rivers  whose  waters  flow  into  the  Arctic  ocean.  Also  draw  a  line  inclosing 
the  tributaries  of  the  Great  Lakes.  This  will  separate  the  Arctic  slope,  the  Gulf  slope,  and  the  valley  of  the  St.  Lawrence 
river. 


THE  LAND  SURFACE  OF  THE  EARTH. 


Mississippi  R.  Ohio  R. 

Bird's-eye  View  of  the  Mississippi  Valley. 


Aileghany  Mta. 


55.  South  America. — South  America  is  triangular  in  shape,  and  broadest  at  the  north. 
Like  North  America,  it  is  an  immense  plain  bordered  by  a  high  mountain  system  on  the 
west  and  a  low  one  on  the  east.  The  Height  of  Land  in  the  center  forms  two  principal 
slopes,  one  to  the  north  and  the  other  to  the  south.  The  crest  is  so  level  that  the  Cas- 
siquiare  river  divides,  sending  part  of  its  waters  to  a  tributary  of  the  Amazon,  and  part  to 
the  Orinoco  river. 


SECTION  ON  THE  EQUATOR 


Profile  of  South  America. 

56.  The  Andes  mountains,  which  are  a  continuation  of  the  Rocky  mountain  system, 
form  the  main  axis.     In  the  Andes  mountains  are  more  than  fifteen  peaks,  each  over  16,000 
feet  high. 

57.  These  mountains  extend  in  two  principal  ranges,  between  which  are  a  number  of 
large  plateaus. 

58.  The  Brazilian  system  of  mountains  lies  on  the  eastern  side  of  the  continent,  and 
forms  an  angle  of  about  45°  with  the  Andean  system. 

59.  The  great  plains  of  the  Orinoco  and  the  Amazon  are  in  the  northern  and  north- 
eastern part.     The  less  extensive  pampas  of  the  La  Plata  are  in  the  southeastern  part. 

60.  Australia. — Australia,  in  its  continental  structure,  resembles  Africa.     Its  moun- 
tains, which  are  near  the  coast,  slope  abruptly  to  the  surrounding  waters. 

61.  The  principal  mountain  system  is  composed  of  the  Australian  Alps,  the  Blue, 
and  the  Liverpool  mountains.     This  system  is  in  the  eastern  and  southeastern  part  of  the 
continent. 

G2.  The  great  plateau  of  Australia  is  in  the  central  part,  traversed  by  low  ranges  of 
mountains.     The  slope  of  this  plateau  is  toward  the  south. 

63.  The  lowland  plains  are  chiefly  in  the  southern  and  southeastern  part.     The  Gulf 
of  Carpentaria  is  also  surrounded  by  a  large,  well-drained  plain. 

64.  Several  large  lakes  are  in  the  southern,  and  a  large  number  of  small  ones,  in  the 
western  part. 


65.  Laws  of  Structure. — A  careful  study  of  the  Relief  Maps  on  pages  140-144  show 
that  the  evolution  of  the  Earth's  features  have  been  in  accordance  with  definite  laws. 

66.  These  are  somewhat  complex,  but  they  involve  the  following  general  principles  : 
Each  continent  has  high  borders  and  a  low  center.     Its  surface,  therefore,  is  basin 

shaped. 

The  greatest  length  of  each  continent  is  in  the  direction  of  its  principal  mountain 
system. 

The  general  shape  of  each  continent  is  that  of  a  triangle. 

The  highest  mountains  border  the  largest  oceans. 

The  greatest  elevations  of  land  are  in  the  Torrid  zone. 

67.  It  must  also  be  kept  in  mind  that  the  continents  were  not  always  where  they  are 
now,  nor  did  they  always  have  the  shape  they  now  have.     Whatever  changes  in  position, 
level,  or  outline  may  have  taken  place,  the  laws  of  structure  have  remained  unaltered. 


WHAT  HAS  BEER  TAUGHT  IN  CHAPTER  III 


The  Earth's  surface  comprises  about  144,- 
OOO,OOO  square  miles  of  water  and  53,OOO,OOO 
of  land.  Of  the  latter  3,OOO,OOO  are  islands. 

The  land  surface  consists  of  triangular  shaped 
continents,  extending  from  the  north  toward 
the  south. 

Three  of  the  continents  are,  for  the  greater 
part,  in  the  North  Temperate  zone,  and  three 
mostly  in  the  Torrid  zone. 

The  land  masses  lying  on  opposite  sides  of  the 
Earth  are  ftnmvn  as  the  Eastern  Continent  and 
the  Western  Continent.  Their  divisions  are  also 
called  continents. 

The  northern  group  of  continents  is  bounded 
by  very  irregular  coasts,  and  is  noted  for  the 
great  number  of  indentations. 

The  Eastern  Continent  extends  from  north- 
east to  southwest,  having  a  lengtli.  of  about  1O,OOO 
miles.  Its  main  axis  is  the  Himalaya  mountain, 
system. 

The  Western  Continent  consists  of  two  tri- 
angles of  land,  extending  from  north  to  south 
about  11,000  miles.  Its  main  axis  is  the  Rocky 
mountain  system. 

Asia  is  the  largest  continent.  Its  highest  point 
is  Mt.  Everest.  From  the  great  plateau  of  the 
Himalaya  mountains, the  surface  slopes  in  every 
direction  toward  the  surrounding  oceans.  The 
Dead  and  Caspian  seas  are  below  the  ocean  level. 

Europe,  in  proportion  to  its  size,  has  a  larger 
coast  line  than  any  other  continent.  Its  main 


axis  is  the  Alpine  system  of  mountains,  from 
ivhose  siimmit  it  slopes  gently  to  the  north  and 
abruptly  to  the  south. 

Africa  is  an  immense  plateau  rising  abruptly 
out  of  the  sea.  Its  main  axis  is  on  the  eastern, 
side.  Its  surface  is  drained  chiefly  by  the  Nile, 
Zambeze,  and  Congo  or  Livingstone  rivers. 

North  America  consists  of  a  great  plain  bor- 
dered on  the  east  and  the  ivest  by  mountain 
chains.  Of  these,  the  Rocky  mountain  system  is 
the  most  extensive.  It  occupies  the  western  part 
of  the  continent. 

The  great  continental  plain  extends  from  the 
Arctic  ocean  to  the  Gulf  of  Mexico.  Its  drain- 
age in  the  southern  part  is  effected  by  the  Missis- 
sippi river  system. 

The  Appalachian  mountain  system  comprises 
several  parallel  ranges  lying  near  tJie  eastern, 
border. 

South  America  resembles  North  America  in  its 
continental  structure,  consisting  of  a  great  plain 
bordered  by  parallel  mountain  ranges. 

Tlie  Andes,  a  continuation  of  the  RocJty  moun- 
tains, forms  the  main  axis. 

The  great  continental  lowlands  extend  front 
the  north  to  south. 

The  Amazon,  Orinoco,  and  La  Plata  rivers 
constitute  the  chief  drainage  systems. 

Atistralia  also  resembles  the  American  conti- 
nents, consisting  of  a  low  plain  bordered  by 
mountains  on  the  east  and  the  west. 


MOUNTAINS,     PLATEAUS,     AND    PLAINS. 


29 


CHAPTER    'IV- 

A.ND 


Section  of  Uintah  Mts.    A,  Green  River  Canon  ;  BB  and  CC,  Strata  worn  by  water ; 
DD,  Mining  Shafts.    The  dotted  lines  show  the  original  fold. 


1.  Mountain  Structure. — It 

is  now  believed  that  mountains 
have  been  formed  by  a  shrinking 
of  the  Earth's  crust,  owing  to  its 
gradual  cooling. 

2.  The    shrinkage    being 
greatest  in  the  interior,  the  over- 
lying strata  are  crushed  together 
sideways. 

3.  Such  side  pressure,  it  is 

evident,  forms  immense  wrinkles 
hundreds  of  miles  wide,  and  often 
many  thousand  miles  long.1 

4.  The  simplest  mountain  range  is   one  consisting  of  a  single  fold  or  wrinkle. 
The  Uintah  range  of  Utah  is  an  example  of  this  kind  of  mountain  formation. 

5.  Oftener,  a  range  consists  of  several  gentle  folds,  as  in  the  case  of  the  Jura  moun- 
tains. 

6.  But  most  frequently,  the  strata,  instead  of  occurring  in  gentle  folds,  are  pressed 
closely  together.    This  kind  of  mountain  structure  is  finely  illustrated  by  the  Coast  Range 
of  California  and  the  Appalachian  system  of  the  Atlantic  coast. 

7.  Mountain  Chains. 
— Mountain    chains  are   al- 
ways composed  of  sediment- 
ary or  stratified  rock.2 

8.  It    is  a  remarkable 
fact    also,    that    the    strata 
which  are  found  in  a  moun- 
tain chain  are  much  thicker 
than  the  same  strata  occur- 
ring elsewhere.3 

9.  Mode  of  Formation. — Mountain  systems,  therefore,  seem  to  be  directly  connected 
with  thick  accumulations  of  sediment. 

10.  These  great  accumulations  always  occur  along  the  shores  of  continents,  where 
everything  washed  from  the  surface  of  the  land  is  finally  deposited  by  the  agency  of  rivers, 
winds,  waves,  and  tides. 


Section  of  Coast  Range  near  Santa  Cruz,  Cal.    The  folded  strata  at  the  surface  have  been  worn  away. 
AA,  Strata ;  SB,  Granite  Axis. 


1  There  is  evidence,  also,  that  in  many  instances  the  crust  of  the  Earth  has  teen  rent,  and  that  either  igneous  or  meta- 
morphic  rock  has  been  forced  upward  through  the  fissure  thus  formed. 

8  In  many  instances  igneous  rock  has  been  thrust  upward  to  the  surface. 

"The  strata  composing  the  Appalachian  system  are  40,000  feet  thick,  while  the  same  strata  on  the  Mississippi  river 
are  only  4,000  feet." — Le  Conte. 


30 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


The  Bad  Lands  of  Dakota. — Water  Sculptured  Mountains. 


11.  We  are  thus  led  to  believe  that  mountain  chains  are  formed  by  the  wrinkling  or 
crumpling  of  the  Earth's  crust  along  those  sea  shores  on  which  accumulations  of  sediment 
have  been  deposited.1 

12.  That  mountains  have  once  been  sea  bottoms  is  shown  by  the  following  facts  : — 
First.  They  are  composed  of  aqueous  (a'-que-us)  rocks. 

Second.  The  fossils  found  within  their  strata  represent  chiefly  those  types  of  life  that 
have  inhabited  the  sea  only. 

Third.  In  several  instances,  strata  of  sea  shells  in  their  natural  state,  mixed  with  sea 
sand,  are  found  in  mountain  ranges  at  an  elevation  of  many  feet  above  the  sea.2 

13.  Laws  of  Position. — By  closely  studying  the  relief  maps,  the  pupil  will  observe 
certain  general  laws  concerning  mountain  structure. 

First.  The  highest  mountain  peaks  occur  in  the  largest  continents. 
Second.  The  most  extensive  systems  are  found  in  the  largest  continents. 
Third.  The  average  height  of  mountains  is'  least  toward  the  poles  and  greatest  toward 
the  equator. 

14.  Continental  Axes. — The  chief  systems  of  a  continent  may  be  considered  its  skeleton, 
inasmuch  as  they  give  to  the  continent  its  general  shape  and  extent.    They  are,  therefore, 
called  the  axes  of  the  continent. 

1  '*It  is  also  certain  that  parallel  ranges  of  a  system  have  been  formed  successively,  and  also  successively  coastward." 
— 'Dana. 

*  Such  deposits  occur  at  San  Pedro,  California.  The  highest  stratum  is  about  four  feet  below  the  surface,  and  is  over- 
laid by  sandstone.  Other  strata  are  found,  at,  irregular  intervals,  below  the  one  mentioned. 


MOUNTAINS,     PLATEAUS,     AND    PLAINS. 


31 


AUSTR'LIA.  EUROPE.   SOUTH  AMERICA.       NORTH  AMERICA.         AFRICA. 


ASIA. 


The  Relative  Proportion  of  Highlands  and  Lowlands. — Highlands  shaded,  the  Lowlands  white. 

15.  The  Rocky  and  Appalachian  systems,  embracing  the  Great  Central  Plain  be- 
tween their  crests,  form  the  general  outline  of  North  America. 

16.  The  Andean  and  Brazilian  systems  constitute  a  frame  upon  which  South  America 
is  modeled ;  having,  like  North  America,  mountain  borders,  between  which  lies  the  great 
continental  plain. 

17.  Europe  and  Asia  are  each  traversed  from  northeast  to  south  west,  by  irregular  and 
complex  systems.   From  the  great,  central  backbone  of  each,  numerous  spurs  project,  forming 
the  numerous  peninsulas  for  which  these  continents  are  noted. 

18.  Africa  and  Australia  resemble  each  other  in  their  mountain  systems,  which  form 
a  rim  surrounding  a  comparatively  low  interior. 

19.  The  importance  of  mountains  cannot  be  too  greatly  estimated.    On  their  presence 
and  position,  the  rainfall,  drainage,  and  climate  of  a  country  almost  entirely  depend. 

20.  The  most  extensive  mountain  system  in  the  world  is  the  Rocky  and  Andean, 
which  has  a  total  length  of  nearly  11.000  miles,  reaching  from  Alaska  to  Patagonia.     In  the 
western  part  of  the  United  States,  there  are  about  50  parallel  ranges  in  this  system. 

21.  The  highest  mountain  peak  in  the  world  is  Mt.  Everest,  situated  in  the  Hima- 
laya range.     Mt.  Everest  is  over  29,000  feet,  or  nearly  5|  miles  high. 

22.  Plateaus. — The  highlands  of  the  Earth  are  not  always  mountains  ;  of  ten,  they  con- 
sist of  vast  upland  plains,  called  plateaus.    These  are  usually  situated  between  those  mountain 
ranges  which  form  the  margins  of  a  mountain  system. 

23.  Thus,  the  Great  Basin  lies  between  the  Rocky  and  the  Sierra  Nevada  mountains. 
The  plateau  of  Thibet  is  situated  between  the  Himalaya  and  the  Kuen  Lun  range.     The 
plateau  of  Bolivia  lies  between  the  two  main  ranges  of  the  Andes.1 

24.  The  surface  of  a  plateau  is  not  necessarily  level ;  on  the  contrary,  it  is  often  rugged 
and  mountainous.   The  Andes  mountains  rest  on  a  high  plateau.    The  Great  Basin  is  covered 
with  a  network  of  mountains  and  valleys. 

25.  About  one-half  of  the  Earth's  land-surface  consists  of  plateaus  and  highlands. 
Generally, they  are  infertile  and  ill-adapted  to  habitation.     They  contain,  however,  nearly  all 
the  mineral  wealth  of  the  world.     Their  proportion  is  approximately  shown  in  the  diagram. 

1  Other  plateaus,  as  the  Mexican,  rise  from  the  sea  level  in  terraces,  or  else  by  a  gradual  and  gentle  slope,  like  the 
"  Plains  "  of  North  America.  The  Plains  rise  imperceptibly  from  the  Mississippi  river  to  the  foot  hills  of  the  Rocky  moun- 
tains, where  their  altitude  is  about  5.000  feet. 


32 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


26.  The  principal  plateaus  of  the  Western  Hemisphere  are  those  of  the  Western  High- 
lands and  Mexico,  in  North  America,  and  the  plateaus  of  Bolivia  and  Titicaca,  in  South 
America. 

27.  The  plateaus  of  the  Eastern  Hemisphere  are  noted  for  their  great  size  and  elevation. 

28.  Africa  is  an  immense  plateau, having  an  elevation  varying  from  2,500  to  8,000  feet.1 

29.  Asia  contains  the  most  notable  plateaus  of  the  world,  both  as  regards  size  and 
elevation.     The  most  prominent  are  the  plateaus  of  Thibet,  Gobi,  Persia,  and  Arabia. 

30.  The    chief  plateaus    of  Europe    are    the  Austrian  plateau  and   the  Spanish 
peninsula. 

31.  Australia  is  skirted  on  the  eastern  and  the  western  border  by  low  plateaus,  having 
an  average  altitude  of  2,000  feet. 

The  following  table  shows  the  most  notable  plateaus  of  the  world  : 


NAMES  OF  PLATEAUS. 

AKEA  IN 
SQUARE  MILES. 

AVERAGE  ELEVATION, 

IN  FEET. 

Africa  (without  lowlands)  

9  500  000 

3  000  to    6  000 

Ai'.ilM  ;i  

700  000 

4  000  to    5  000 

Gobi  

400  000 

4  500  to    5  500 

Persia  

300  000 

3  000  to    4  000 

Spanish  Peninsula.  

225  000 

2  500  to    4  000 

Mexican  

180  000 

G  000  to    8  000 

Thibet  

160  000 

11  000  to  12500 

Bolivia  

120,000 

10  000  to  13  000 

Great  Basin  

120,000 

4  500  to    6  000 

32.  Plains. — Plains  and  lowlands  form  the  remaining  half  of  the  land-surface.     They 
are  large  tracts,  usually  of  level  country,  having  an  elevation  of  not  more  than  1,000  feet. 

33.  There  are  two  great  classes  of  plains,  differing  both  in  origin  and  general  features. 

34.  Alluvial  Plains. — Alluvial  plains  owe  their  origin  to  rivers  whose  waters  carry 
material  from  the  mountains  and  deposit  it  in  places  where  the  current  runs  less  swiftly. 
This  occurs  chiefly  at  the  mouths  of  rivers  and  along  their  lower  courses.     Alluvial  plains 
are  always  level. 

35.  The  plains  of  the  Amazon,  the  Orinoco,  the  La  Plata,  and  also  those  of  China  and 
Hindostan,  are  examples  of  this  class.     Much  of  the  Mississippi  valley  has  also  been  formed 
in  a  similar  manner. 

36.  Marine  Plains. — Marine  plains  are  old  sea  bottoms  which  have  been  gradually 
lifted  above  the  sea  level. 

37.  The  plains  surrounding  the  Caspian  and  Baltic  seas,  the  northern   part  of  the 
Mississippi  valley,  and  especially  those  which  border  large  oceans,  are  examples  of  marine 
plains. 


1  Sahara,  in  the  northern  part  of  Africa,  has  an  average  altitude  of  1,500  feet. 


MOUNTAINS,     PLATEAUS,     AND    PLAINS. 


33 


The  fcneppes  or  Plains  of  Siberia,  looking  south  toward  the  Altai  mouutaius. 


38.  Marine  plains, 
especially    those    of 
recent    formation, 
are  often  sandy  and 
sterile.      Their   soils 
generally    contain 
large    quantities    of 
salt,   soda,   and  pot- 
ash.1 

39.  The  Steppes 
of  Russia  and  Si- 
beria    are    marine 
plains,  but  they  have 
been,  in  many  places, 
covered    with    sedi- 
ment brought  down 
by  the  rivers  flowing 
through  them. 

As  the  altitude  in- 
creases, the  plain 
generally  becomes 
hilly.  Such  is  the 
case  with  the  Sibe- 
rian and  the  North 
American  plains. 

40.  The  plains  of  North  America  lie  between  its  two  mountain  systems.    In  the 
higher  portions,  they  are  covered  with  forests  of  valuable  timber  ;  but  toward  the  north,  they 
become  a  dreary,  frozen  waste. 

41.  Much  of  the  southern  portion  is  a  vast  cypress  swamp  whose  surface  is  scarcely 
above  the  sea  level.2 

42.  The  central  and  southern  portions  of  the  plains  of  North  America  supply  nearly 
one-third  of  the  wheat  and  corn,  and  about  one-half  of  the  cotton,  used  in  the  civilized  world. 
The  level  plains  of  North  America  east  of  the  Mississippi  are  called  prairies  ;  those  west  of 
the  Mississippi,  "  the  plains ." 

43.  The  plains  of  South  America  also  lie  between  the  continental  mountain  systems. 
Those  of  the  Orinoco  are  alluvial.     They  are  called  llanos  (lyah'-noce).     For  a  few  months, 
they  dry  and  parch  under  the  scorching  rays  of  a  tropical  sun,  until  they  resemble  a  desert. 

44.  Then,  the  rainy  season  sets  in ;  the  streams  overflow  their  banks ;  and,  save  here 
and  there  a  projecting  knoll,  the  whole  country,  as  far  as  the  eye  can  reach,  is  under  water.3 

1  The  plain  which  constitutes  the  southwestern  part  of  California  is  a  remarkable  example  of  recent,  marine  plain. 
Layers  of  sea  shells  in  a  perfect  state  of  preservation  are  frequently  found  at  a  distance  of  but  a  few  feet  from  the  surface. 
The  unpetrified  skeletons  of  whales  are  found  in  large  numbers,  some  at  an  altitude  of  several  hundred  feet  above  the  sea 
level. 

'•>  These  cypress  swamps  are  called  everglades.     The  great  Dismal  Swamp  of  Virginia  is  a  notable  example. 

8  Just  before  the  wet  season  begins,  the  herds  of  cattle  and  horses  stampede  ;  and  in  due  time,  reach  the  foothills  of 
the  plateaus.  The  few  that  lag  behind,  usually  perish.  It  is  not  an  uncommon  sight  to  see  a  small  hillock  which  projects 
above  the  surface  of  the  water,  crowded  with  wild  animals  of  every  species,  struggling  with  one  another  to  keep  a  foothold 
above  the  water.  Alligators  and  other  reptiles  that  have  remained  dormant  during  the  drought,  appear  in  great  numbers. 


34  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 

45.  The  plains  of  the  Amazon  are  covered  with  forests,  so  dense  and  impenetrable, 
that  the  streams  of  water  flowing  through  them  are  often  the  only  highways.     These  plains 
are  called  selvas.     From  them  are  obtained  a  great  variety  of  ornamental  and  dye  woods. 
The  India  rubber  tree  (Siphonia  elastica)  is  abundant.1 

46.  The  plains  of  the  La  Plata,  called  pampas,  have  an  extent  of  about  175,000  square 
miles.     They  are  well  drained,  and  afford  pasturage  to  immense  herds  of  cattle,  which  out- 
number those  in  all  other  parts  of  the  world  together.     Millions  are  slaughtered  annually 
for  their  hides,  horns,  and  beef.     Neither  the  rainy  nor  the  dry  season  is  severe.    Hence,  the 
pampas  are  the  most  valuable  part  of  the  continent,  in  respect  to  their  natural  resources. 

47.  The  three  plains  of  South  America  are  not  separated  by  any  distinct,  physical 
features. 

48.  The  northern  parts  of  Europe  and  Asia  constitute  an  immense  plain  bordering 
the  Arctic  ocean.     The  three  divisions  of  this  plain  comprise  the  forests  of  the  south,  the 
agricultural  lands  of  the  middle,  and  the  tundras  of  the  northern  part. 

49.  The  Ural  mountains,  crossing  this  plain  at  right  angles  to  its  line  of  greatest  length, 
form  a  ridge  corresponding  to  the  Height  of  Land  of  the  American  plains. 

50.  The  higher  portions  of  this  plain  are  the  steppes  (steps).     That  part  bordering  the 
Arctic  ocean  is  generally  known  as  the  tundras  (toon-drahs). 

51.  In  summer,  the  tundras  are  swamps  in  which  nothing  but  the  lowest  forms  of 
vegetable  life,  such  as  mosses  and  lichens,  can  exist.     In  winter, they  are  frozen  wastes.2 

52.  Africa  contains  no  extensive  plains.     There  are  lowlands  bordering  the  ocean,  a 
number  of  alluvial  plains  along  the  larger  rivers,  and  parts  of  the  Sahara;  but  there  are  no 
such  plains  as  characterize  the  other  continents. 

53.  Of  the  river  valleys,  that  of  the  Nile  is  the  most  important.     This  valley,  owing  to 
the  annual  overflow  of  the  Nile,  is  exceedingly  fertile,  and  produces  valuable  crops  of  grain.8 
Each  flood  deposits  a  fresh  layer  of  soil  on  the  surface  of  the  valley.     Were  it  not  for  this 
overflow,  the  valley  of  the  Nile  would  be  sterile  and  uninhabitable. 

54.  The  oases  of  the  Great  Desert  are  remarkable  for  their  perpetual  fertility.     They 
are  well  supplied  with  water  all  the  year,  and  in  consequence,  present  a  strong  contrast  to 
the  surrounding  desert. 

55.  In  structure,  the  oases  are  depressions  in  the  limestone  formation.     A  stratum  of 
clay  and  sand  forms  the  bottom  of  the  basin,  holding  the  water  that  finds  its  way  from  the 
surrounding  highlands.4 

1  The  only  inhabitants,  except  the  traders  who  live  along  the  navigable  rivers,  are  savages  of  the  lowest  type  of 
humanity. 

2  The  cause  of  these  conditions  is  remarkable  and  interesting.     The  mouths  of  the  rivers  flowing  into  the  Arctic 
ocean  are  in  high  latitude,  and  hence  are  frozen  during  a  great  part  of  the  year.     The  rivers  having  no  open  channel,  over- 
flow their  banks  and  convert  the  whole  country  into  a  vast  morass.     It  was  in  the  tundras  of  the  Lena  river  that  Lieut.  De 
Long  and  his  party,  of  the  ill-fated  Jeannette,  perished. 

In  their  general  features,  the  Arctic  plains  of  the  Eastern  Hemisphere  do  not  differ  from  the  North  American  plains  in 
the  same  latitude. 

3  The  rising  of  the  river  begins  in  June  and  continues  until  the  middle  of  September,  when  it  begins  to  subside.     The 
water,  at  the  highest  stage, is  sometimes  30  feet  above  low  water  level. 

4  There  are  about  30  oases,  of  which  20  are  inhabited.     The  largest,  Ammonium,  contains  several  towns,  and  has  an 
area  of  3,000  to  4,000  square  miles.     The  oases  are  stopping-places  for  caravans,  where  they  obtain  supplies  of  food  and 
water. 


MOUNTAINS,     PLATEAUS,     AND    PLAINS. 


35 


56.  The  lowlands  of  Australia  are  the  alluvial  valleys  of  the  Murray  river  and  its 
tributaries.     These  valleys  are  extremely  fertile  and  are  productive  of  great  wealth. 

57.  The  great  plains  of  Australia,  however,  lie  in  the  interior  of  the  continent.     During 
the  rainy  season,  they  are  more  or  less  productive,  but  in  the  summer  they  soon  become 
parched  and  desolate. 

58.  There  are  also  large,  sandy  plains  containing  salt  lakes,  but  destitute  of  all  vegeta- 
tion, save  a  long,  stiff  grass,  called  spinif ex.     Swarnpy  lands  are  occasionally  found  in  these 
plains.     Owing  to  the  great  heat  and  the  lack  of  water,  the  central  Australian  plains  are 
uninhabitable.1 


WHAT  HAS  BEEN  TAUGHT  IN  CHAPTER  IY, 


That  mountains  have  been  formed  by  the 
crust  of  the  Earth  shrinking  upon  a  contract- 
ing interior,  thus  producing  immense  folds,  or 
wrinkles. 

The  wrinkles  or  mountains  thus  formed  are 
made  by  side  crushing,  and  frequently  igneous 
rock  is  thrust  upward  through  rents  found  in 
the  broken  strata. 

Sometimes  the  mountain  chain  consists  of  a 
single  fold  or  plication,  but  oftener,  of  several 
folds  crushed  together. 

Mountain  chains  are  composed  of  enormous 
thicknesses  of  sedimentary  rock. 

The  mountain  systems  of  a  continent  form  the 
skeleton,  which  gives  the  continent  its  outline. 

The  ranges  composing  a  mountain  system  are 
generally  parallel  to  one  another. 

The  chief  mountain  systems  of  the  Western 
Hemisphere  extend  nearly  north  and  south. 

Tfiose  of  the  Eastern  Hemisphere  extend  from 
the  northeast  to  the  southwest. 

Plateaus  are  elevated  surfaces  which  usually 
extend  between  parallel  mountain  ranges. 

Tlie  chief  plateaus  of  the  Western  Hemisphere 
are  the  Western  Highlands  and  Mexican  pla- 
teau of  North  America,  and  the  Bolivian  and 
Andean  plateaus  of  South  America. 

Those  of  the  Eastern  Hemisphere  are  Arabia, 
Gobi,  Persia,  and  Thibet;  the  latter  being  the 
highest  plateau  in  the  world. 


Their  surfaces  are  not  always  level,  being 
frequently  rugged,  and  often  studded  with  moun- 
tain peaks  and  short  mountain  ranges. 

Plains  are  formed  either  by  the  deposition 
of  sediment  along  the  course  of  a  river,  or  by 
the  elevation  of  sea  bottoms. 

Many  marine  plains  have  been  subsequently 
shaped  by  rivers.  .Recent  marine  plains  have 
usually  a  sandy  soil  and  are  frequently  ster- 
'ile. 

The  chief  plain  of  North  America  extends 
from  the  Arctic  ocean  on  the  north  to  the  Gulf 
of  Mexico  on  the  south. 

The  principal  plain  of  South  America  extends 
from  the  mouth  of  the  Orinoco  to  the  mouth  of 
La  Plata  river,  being  drained  by  the  Amazon, 
Orinoco,  and  La  Plata  rivers. 

The  largest  plains  of  Europe  and  Asia  border 
the  Arctic  ocean,  and  rise  from  the  sea  in  suc- 
cessive terraces. 

The  plains  of  southern  Asia  are  chiefly 
alluvial,  and  constitute  the  most  thickly  inhab- 
ited part  of  the  continent. 

The  oases  of  the  Great  Desert,  the  most  re- 
markable of  African  plains,  ore  depressions 
surrounded  by  limestone  formation,  and  under- 
laid with  a  stratum  of  clay. 

The  plains  of  Australia  are  in  the  interior 
of  the  continent.  They  are  generally  destitute  of 
vegetation  and  are  subject  to  excessive  drought. 


1  The  average  daily  temperature  frequently  exceeds  110°  F.     Howlitt,  an  explorer,  states  that  l&e  has  recorded  a  tem- 
perature of  139°  P. 


36  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


CHAPTER 


1.  Area  and  Classification.  —  About  3,000,000  square  miles,  or  nearly  one-seventeenth 
of  the  land  surface  of  the  Earth,  consists  of  islands. 

2.  These,  with  respect  to  their  structure  and  position,  are  either  continental  or  oceanic. 

3.  Continental  Islands.  —  Continental  islands  are  generally  elongated  in  shape,  and 
are  parallel  to  the  coasts  near  which  they  lie.     In  structure,  they  are  usually  like  the  neigh- 
boring continents. 

4.  Comparing  their  strata  with  those  of  the  adjacent  continent,  we  find  not  only  similar 
species  of  living  plants  and  animals,  but  also  the  same  kind  of  fossils. 

5.  From  this  evidence,  continental  islands  are  believed  to  be  partly  submerged  mountain 
chains,  belonging  to  the  continent  to  which  they  are  adjacent. 

6.  On  any  map  of  the  Western  Hemisphere,  trace  a  continuous  line  from  Yucatan, 
through  the  West  Indies  and  the  Lesser  Antilles  (ahn-teel),  to  the  mouth  of  the  Orinoco 
river.     This  chain  of  islands  is  a  spur  of  the  Rocky  mountain  system. 

7.  On  a  map  of  the  Eastern  Hemisphere,  also  trace  a  line  from  Kamtschatka,  through 
the  Kurile  islands,  the  Japan  Empire,  the  Liukiu  and  Philippine  (fil'ip-pm)  islands.     This  is 
a  mountain  range,  lying  parallel  to  the  eastern  shores  of  Asia. 

8.  Sumatra,  Java,  and  the  chain  lying  to  the  eastward,  form  a  mountain  range  parallel 
to  the  one  which  constitutes  the  peninsula  of  Malacca. 

9.  This  range  may  be  traced  northward  to  the  divide  between  the  Irrawaddy  and  the 
Ganges  river. 

10.  From  the  western  extremity  of  the  Aliaskan  peninsula,  a  chain  of  islands  extends 
nearly  to  Asia.     This  chain  belongs  to  the  Rocky  mountain  system. 

11.  The  chains  of  islands  just  described  are  both  mountainous  and  volcanic.     In  fact, 
they  contain  nineteen-twentieth  s  of  the  volcanoes  in  the  world.     In  more  than  one  instance, 
every  island  of  the  chain  is  a  volcanic  cone. 

12.  There  is   one  group   of  continental  islands  which  is  neither  mountainous  nor 
volcanic.     It  comprises  the  islands  of  the  Arctic  archipelago.1 

13.  These  islands  form  a,  partly  submerged  marine  plain,  which  seems  to  be  a  continua- 
tion of  the  Arctic  plain  of  North  America.     Although  not  mountainous,  their  surface  is 
rugged,  and,  in  many  instances,  "reefs  of  rock  rising  abruptly  out  of  the  sea,  form  their 
natural  boundaries." 

1  Greenland,  Cumberland,  and  Banks  islands,  together  with  the  archipelago  lying  northeast  of  North  America,  consti- 
tute the  exception  mentioned.  Comparatively  little  is  known  about  this  group  of  islands.  Baron  Nordenskjold,  who 
penetrated  Greenland  to  a  distance  of  100  miles,  found  the  interior  a  barren  plateau,  covered  with  ice  and  enow.  According 
to  his  opinion,  Greenland  consists  of  a  number  of  islands  joined  by  a  perpetual  bond  of  ice. 


ISLANDS  . 


37 


14.  Oceanic  Islands. — Nearly  all  of  the  oceanic  islands  are  in  the  Pacific  ocean,  at 
a  considerable  distance  from  any  continent.     These  groups  constitute  the  divisions  of  Poly- 
nesia and  Micronesia. 

15.  Oceanic  islands  differ  from  continental  islands  in  structure  ;  for  while  the  former 
are  similar  to  the  main  land  near  by,  the  latter  are  formed  either  of  volcanic  ejections,  or  of 
limestone. 

16.  The  islands  formed  of  volcanic  ejections  are 
usually  active  volcanoes  having  a  considerable  alti- 
tude ;  those  composed  of  limestone  are  the  low  tops 
of  coral  (kor'al)  reefs,  and  are  called  coral  islands. 

17.  Coral  Islands. — Coral  islands  are,  in  many 
respects,  the  most  interesting  features  in  the  world. 
Each   island  is  an  irregular  ring  of  land,  usually 
broken  in  several  places,  and  having  a  surface  only 
a  few  feet  above  the  sea  level. 

18.  The  island  forming  this  ring  is  called  an 
atoll  (a-tol1) ;  the  lake  inclosed  by  the  atoll,  a  lagoon 
(Id-goon1). 

19.  Within  the  lagoon  the  water  is  shallow, 
never  exceeding  forty  or  fifty  fathoms  in  depth. 
Outside  the  lagoon  it  is  unfathomable  at  a  short 
distance  from  the  shore. 


Coral  Keef  and  Lagoon. 


20.  The  atoll  is  nearly  always  covered  with  a  luxuriant  growth  of  vegetation,  limited 
however,  to  a  very  few  species.1 

21.  Structure. — In  many  instances,  a  volcanic  mountain  occupies  the  center  of  the 
lagoon.     This  fact  is  an  important  one,  because  it  tells  the  wonderful  story  of  the  building 
of  the  island. 

22.  The  reefs  composing  the  island  are  limestone,  and  the  limestone  has  been  taken 
by  the  coral  polyp,  atom  by  atom,  out  of  the  water  to  make  its  skeleton. 

23.  The  Coral  Polyp.— The  coral 
polyp  is  a  zoophyte,  a  form  of  animal  life 
which  may  be  likened  to  a  tree,  with 
its  trunk  and  multitude  of  branches. 
The  mouths  of  the  coral  polyp  com- 
pletely cover  its  upper  surface,  closely 
resembling  the  petals  of  flowers,  which 
they  rival,  both  in  color  and  beauty. 


A  A,  Section  of  reef ;  B  S,  Lagoon  ;  C,  Volcanic  Mountain ,  D  Z>,  Ocean  Waters. 
Section  of  a  Coral  Island. 


24.  In  a  single  community  the  growth  of  the  coral  is  chiefly  upward  ;  but  when  multi- 
tudes of  such  communities  live  side  by  side,  their  branches  interlock,  and  finally  form  one 
compact  mass. 


1  There  are  seldom  more  than  forty  or  fifty  species, — often  not  more  than  half  that  number.     These  consist  of  the 
cocoa  and  date  palms,  the  bread-fruit  tree,  the  banana,  and  a  number  of  less  important  kinds. 


38 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Vegetation  of  a  Coral  Island  in  Polynesia. 


25.  Thus,  in  time,  the  fringe  of  coral  becomes  a  solid  ring-like  wall,  completely  encircling 
the  island  on  whose  shores  the  seemingly  insignificant  animal-flower  was  cast. 

26.  Coral  polyps  sometimes  multiply  by  eggs,  or  egg-germs,  and  these  are  distributed 
along  the  shore  by  winds  and  waves.    They  multiply  chiefly,  however,  by  the  process  of  bud- 
ding and  branching  just  described. 

27.  Although  the  coral  polyps  cannot  live  more  than  120  feet  below  the  surface  of  the 
water,  yet  the  reefs  they  have  built  extend  thousands  of  feet  in  depth.    How,  then,  did  the 
polyp  reach  these  depths  ?    We  shall  see. 

28.  Formation  of  the  Island. — The  researches  of  Darwin  have  led  to  the  discovery 
that  the  islands  land  volcanic  cones,  along  whose  shores  the  coral  polyps  built,  have  been 
gradually  sinking. 

29.  As,  little  by  little,  these  islands  sunk,  the  coral  built  upwards,  always  keeping  near 
to  the  surface  of  the  water,  but  never  building  above  it.    In  time,  the  waves  lashing  the  crests 
of  the  reefs,  broke  off  masses  and  piled  them  up,  just  as  now  the  storm  waves  sometimes 
throw  up  bars  of  sand  and  gravel  on  our  coasts. 

30.  Waves  and  migrating  birds  scattered  over  the  island  the  seeds  brought  from  other 
lands.     In  the  course  of  years,  these  covered  the  island  with  a  mantle  of  verdure. 

31.  Sometimes,  the  volcanic  mountain  reaches  a  great  elevation ;  often,  its  summit  is 
scarcely  above  the  water  level,  while  in  other  instances,  it  is  entirely  below  the  surface,  and 
covered  with  coral  growths. 

32.  Apparently  the  Polynesian  and  Micronesian  groups  of  islands  consist  of  an  immense 
plateau  about  6,000  miles  long  and  2,000  miles  wide,  almost  wholly  submerged. 


ISLANDS.  3£ 

33.  Examine  a  map  of  Oceanica  and  you  will  not  fail  to  notice  that  the  islands  com- 
posing each  group  are  in  regular  lines,  just  such  lines  as  would  appear  above  the  surface 
of  the  ocean,  if  the  plateau  of  Thibet,  for  instance,  were  submerged  till  only  the  highest 
crests  were  out  of  water. 

34.  Fringing  Reefs. — Another  kind  of  coral  architecture,  namely,  the  reefs  which 
often  skirt  the  shores  of  continents,  possesses  more  than  ordinary  interest.     They  seldom 
exceed  half  a  dozen  miles  in  width,  while  they  are  sometimes  many  hundred  miles  long. 

35.  The  West  Indies  and  the  Bermuda  islands  are  fringed  with  these  reefs.     The 
peninsula  of  Florida  owes  its  shape  chiefly  to  them.    On  the  northeastern  shores  of  Australia,, 
the  coral  reef  exceeds  1,250  miles  in  length.1 

36.  Wave-formed  Islands. — The  rivers  of  the  Atlantic  slope  of  the  United  States  are 
constantly  depositing  their  sediment  all  along  its  eastern  shores.     But  while  the  river  cur- 
rents tend  to  carry  it  seaward,  the  waves  and  wind  push  it  landward. 

37.  Consequently,  between  the  two  opposing  forces,  a  long  reef  or  sand-spit  is  thrown 
up  along  the  shore  and  parallel  to  it.     The  sand-spits  opposite  Hatteras  inlet  are  fine 
examples  of  wave-formed  islands. 


WHAT    HAS    BEEN    TAUGHT    IN    CHAPTER    Y. 


Islands,  constituting  about  one-seventeenth  of 
the  land  surface  of  the  Earth,  have  an  aggre- 
gate area  of  3,OOO,OOO  square  miles. 

Continental  islands  always  lie  near  and  par- 
allel to  the  continents  of  which,  in  structure,  they 
form  a  part. 

Neither  the  roclcs  that  compose  continental 
islands,  nor  the  forms  of  life  upon  them,  differ 
from  those  of  the  continents  near  which  they  lie. 

They  constitute  partly  submerged  mountain 
chains  and  plateaus. 

Nearly  all  continental  islands  are  volcanic, 
and  they  contain  nineteen-twentieths  of  the  vol- 
canoes of  the  'globe. 

Oceanic  islands  are  always  at  a  great  dis- 
tance from  any  large  body  of  land,  nearly  all 
of  them  being  in  the  Pacific  ocean. 


The  various  islands  composing  the  groups  are 
usually  ranged  in  parallel  lines. 

Oceanic  islands  consist  either  of  volcanic  cones, 
or  else  reefs  of  coral  limestone. 

The  coral  island  is  usually  a  ring-shaped  reef 
inclosing  a  shallow  lagoon,  in  the  center  of  which 
there  is  a  volcanic  mountain. 

Each  atoll  is  the  work  of  the  coral  polyp, 
ivhich,  building  in  shalloiv  water,  surrounded 
the  island  with  a  reef  of  coral  limestone. 

While  the  island  slowly  sank,  the  coral  polyp 
built  as  rapidly  towards  the  surface. 

Many  continental  shores  are  fringed  with 
coral  reefs,  formed  in  much  the  same  man- 
ner as  the  coral  islands. 

The  vegetation  of  coral  islands  is  limited  to- 
a  few  species  of  palms. 


1  "In  the  tropical  Pacific  every  high  island  or  previously  existing  land  is  surrounded  by  a  reef  which  attaches  itself  to 
the  shore  line  and  extends  outward  on  every  side  just  beneath  the  water  level,  as  far  as  the  condition  of  depth  will  allow, 
forming  a  submarine  platform  bordering  the  island  or  other  land." 

"  In  many  cases,  besides  the  fringing  reef  there  is  another  reef  surrounding  the  island  like  a  submarine  rampart,  at 
the  distance  of  from  ten  to  fifty  miles.  As  the  reef  rises  nearly  to  the  surface  of  the  sea,  its  position  is  indicated  by  a  snowy 
girdle  of  breakers  surrounding  the  island,  and  the  snowy  girdle  is  gemmed  with  wave  formed  green  islands.  Within  this 
girdle,  and  between  the  rampart  and  the  island,  there  is  a  ship  canal  twenty  or  thirty  fathoms  deep.  Through  breaks  in  the 
coral  rampart,  ships  enter  this  channel,  and  find  secure  harbor  in  a  stormy  sea  " — Le  Conte. 

Circular  reefs  or  atolls  have  already  been  described.     Every  circular  reef  marks  the  locality  of  a  sunken  island. 


40 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


CHAPTER     VI. 


180  1BO  140  120  100  80      i    \  60  40  80 


40  60  80  100  120  140  160  180 


Zinet  of  Equal  ~EaM  Declination 

Line*  of£gual  West  declination 

linaiiun 


EQUAL  MAGNETIC       '  = 

DECLINATION 

EPOCH  188O.     v 

80      -. 


C./iorp     \ 

S3        2(1        is       1 


1.  Properties. — A  magnet  is  usually  a  bar  of  steel  which  has  the  property  of  drawing 
towards  itself  pieces  of  iron  or  nickel.     When  balanced  and  suspended  by  a  string,  the  mag- 
net comes  to  rest,  pointing  in  an  unvarying  direction. 

2.  The  word  magnet  is  derived  from  Magnesia,  a  city  of  Asia  Minor,  near  which  lode- 
stone,  a  kind  of  iron  ore  having  magnetic  properties,  was  originally  found. 

3.  An  artificial  magnet  is  usually  a  piece  of  steel  which  has  been  magnetized  by  elec- 
tricity, or  by  rubbing  its  ends  with  another  magnet.     Steel  or  nickel  must  be  used,  because 
these  metals  retain  their  magnetism  permanently,  while  soft  iron  does  not. 

4.  If  iron  filings  are  sprinkled  on  a  piece  of  paper  under  which  a  bar  magnet  lies,  they 
will  cluster  in  curved  lines  about  the  ends  of  the  bar,  while  few  or  none  of  the  filings  adhere 
to  the  center,  showing  that  magnetism  appears  to  be  strongest  at  the  ends  of  the  bar. 

5.  Polarity. — The  two  ends  of  the  bar,  at  which  the  magnetism  is  strongest,  are  the 
poles  of  the  magnet.     For  convenience,  they  are  called  the  north-seeking  or  — ,  and  the 
^outh-seeking  or  +  poles.  • 

G.  The  like  poles  of  two  magnets  repel,  the  unlike  poles  attract  each  othe^     Either 
pole  attracts  bits  of  unmagnetized  iron  and  nickel. 

7.  If  a  small  piece  of  steel,  as  half  a  knitting-needle,  be  suspended  by  a  strand  of  silk 
and  exactly  balanced,  it  will  rest  indifferently  in  any  position  to  which  it  may  be  pointed. 


MAGNETISM. 


Iron  filings  strewn  upon  a  sheet  of  paper  held  over  a  Magnet. 


8.  But  if  the  ends  of  the  needle  be  rubbed, 
one  by  the  marked,  the  other  by  the  unmarked 
end  of  a  magnet,  the  needle  no  longer  remains 
indifferent  to  its  position  :  it  turns  until  it  points 
nearly  or  quite  north  and  south. 

9.  No  matter  how  carefully  you  may  change 
its  position,  the  needle  will  swing  back  until  it 
regains  its  fixed  direction. 

10.  It  does  not  even  remain  in  balance, 
for,  as  soon  as  the  needle '  is  magnetized,  the 
north-seeking  end  (north  of  the  equator)  turns 
downward  or  "dips." 

11.  The  Compass. — A  compass  consists  of 
a  small  magnet,  called  a  needle,  so  poised  on  a 
pivot  that  it  turns  freely.    In  the  mariner's  com- 
pass the  needle  is  fastened  to  a  circular  card,  on  whose  circumference   the  names  -of  the 
cardinal  points  and  their  subdivisions  are  printed.     Both  needle  and  card  turn  on  the  pivot.1 

12.  No  matter  in  what  part  of  the  world  the  compass  may  be — on  sea  or  on  land — the 
needle  always  seeks  its  north-and-south  position. 

13.  This  wonderful  property  of  the  compass-needle  makes  it  of  priceless  value  to  the 
sailor ;  as  without  it,  the  navigation  of  the  ocean  would  almost  be  an  impossibility. 

14.  Magnetic  Variation. — But  the  compass-needle  does  not  always  point  exactly  north 
and  south.     In  fact,  there  are  but  very  few  places  on  the  Earth  where  it  does,  and  these 
places  are  constantly  changing. 

•    15.  Look  on  the  map  at  the  beginning  of  this  chapter  and  find  the  line  marked  0°.     In 

1880,  everywhere  along  this  line  the  compass- 
needle  pointed  due  north  and  south.  This  line 
is  called  the  line  of  no  declination. 

16.  In  all  places  east  of  this  line,  the 
north-seeking  end  of  the  needle  turns  a  little 
towards  the  west ;  in  all  places  \vest  of  the  line 
it  is  deflected  eastward.   The  figures  at  the  end 
of  each  line  tell  how  many  degrees,  east  or 
west,  the  direction  of  the  needle  varies  from 
the  true  meridian. 

17.  Magnetic    Poles. — These    lines    ap- 
proach towards  the  north,  and  finally  intersect 
in  the  western  part  of  Boothia  Land.   The  point 
of  intersection  is  the  magnetic,  North  Pole.12 

18.  Magnetic    Dip.  —  At   the    magnetic 
The  compass.                                    North  Pole,  a  needle  suspended  as  you  see  in  the 

1  The  compass  box  is  so  mounted  that  it  always  remains  level.  The  box  is  sometimes  filled  with  a  liquid  on  which 
the  card  and  needle  almost  float, — only  a  very  slight  weight  resting  on  the  pivot. 

3  The  latitude  of  the  magnetic  North  Pole  is  70°  8'  N. ;  its  longitude  is  96°  45'  W.  This  position  has  been  determined 
ty  actual  observation.  The  exact  locality  of  the  magnetic  South  Pole  is  only  theoretically  known. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Position  of  the  needle  at  different  parts  of  the  Earth. 


cut,  has  a  vertical  position,  the  north-seeking  or  —  end  being  down.  Going  southward,  how- 
ever, it  gradually  recovers  its  position,  until,  at  a  point  near  the  equator  it  ceases  to  dip 
and  its  position  is  horizontal. 

19.  Going  still   farther  southward,  the  south- 
seeking  or  +  pole  now  dips.     The  dip  constantly 
increases  till  the  south  magnetic  pole  is  reached, 
where  the  needle's  position  is  again  vertical ;  this 
time  the  south-seeking  pole  is  downward.* 

20.  The  Earth's  Directive  Force. — Thus  we 
see  that  the  Earth  itself  has  all  the  properties  of  a 
magnet.     Like  a  magnet  it  has  two  magnetic  poles, 
and    these  affect    the  compass-needle  in  just  the 
same  manner  as  does  any  other  magnet. 

21.  Change  in  Variation. — We  must  keep  in  mind  that  not  only  is  the  compass  vari- 
ation constantly  changing,  but  also  that  the  rate  of  change  is  seldom  alike  in  any  two  places 
distant  from  each  other,  and  is  itself  constantly  changing.     In  fact,  there  are  no  factors  or 
values  pertaining  to  magnetism  that  are  not  subject  to  frequent  and  unexpected  changes.2 

22.  Periodic  Variations. — There  is  another  series  of  magnetic  variations  having  great 
interest,  because  they  are  governed  by  forces  beyond  the  influence  of  the  Earth.     These  are 
the  daily,  the  monthly,  the  yearly  variations,  and  the  period  of  magnetic  storms. 

22.  The  first  three  of  these,  though  very  slight,  are  regular  in  occurrence,  and  toler- 
ably uniform.  It  is  thought  that  they  are  duo  to  the  influence  of  the  sun  and  the  moon. 
They  are  vibrations  of  the  needle  rather  than  permanent  variations. 

24.  Magnetic  Storms. — About  every  eleven  years  the  magnetic  needle  is  subject  to 
violent  disturbances  which  are  closely  connected  with  sun-spots.     These  disturbances  are 
called  ''magnetic  storms." 

25.  Whenever  a  sun-spot  shows  signs  of  agitation  or  rapid  change,  a  powerful  effect 
upon  the  magnetic  needle  is  noticeable.     Quiet  sun-spots,  on  the  contrary,  have  little  or  no 
effect. 

26.  During  a  magnetic  storm,  the  needle  trembles  constantly  and  swings  on  its  pivot 
over  an  arc  measuring  sometimes  one  or  two  degrees.     The  Aurora  Borealis  is  often  visible 
at  the  time  of  a  severe  storm,  and  telegraph  lines  frequently  refuse  to  work. 

27.  Thus  we  see  that  the  magnetic  needle  never  rests,  but  forever  swings  back  and 
forth,  controlled  by  a  force  we  know  not.     Fortunately  for  those  who  use  the  compass,  these 
changes  are  always  slight — sometimes  almost  imperceptible — yet  they  nevertheless  exist. 

1  Ship  compasses  are  so  constructed  that  the  needle  and  card  are  always  horizontal.  In  the  Arctic  regions, the  vertical 
force  is  so  strong,  and  the  horizontal  force  so  weak,  that  the  compass-needle  will  scarcely  turn  on  the  pivot.  On  whaling 
vessels,  the  helmsman  frequently  attaches  a  cord  to  the  compass-box,  giving  the  latter  an  occasional  shake,  in  order  that  the 
needle  may  settle  in  some  definite  direction. 

8  The  following  table  shows  the  changes  in  variation  at  Paris  during  the  last  300  years  : 
Variation  in  1580,  11° 
1618,    8° 
1663,    0° 


20' 

0' 
0' 


Variation  in  1700,  8°  10 '  W. 
1780,  19°  55'  W. 
1814,  22°  34'  W. 


Variation  in  1816,  22°  25 '  W. 
1823,  22°  23 '  -W. 
1828,  22°  5 '  W. 


Variation  in  1829, 22°  12'  W. 
1835,22°  4'W. 
1854,  22°  10 'W. 


In  some  parts  of  the  United  States,  the  annual  change  is  7^'  (angular  measure).  In  New  Mexico  and  Arizona,  there 
has  been  no  change  for  several  years.  The  yearly  increase  is  greater  toward  the  northern  part  of  the  continent.  On  the 
Pacific  coast,  the  easterly  variation  is  increasing;  on  the  Atlantic  coast  and  the  Mississippi  valley,  the  westerly  variation  is 
increasing. —  U.  8.  Coast  Survey — Report  for  1883. 

It  is  evident  that  the  map  used  to  illustrate  this  chapter  will  be  useless  ten  years  hence. 


MAGNETISM. 


43 


28.  What  magnetism   is  and  why  it  so  mysteriously  controls  the  piece  of  steel  in 
which  it  resides,  are  questions  that  cannot  be  answered.     We  know  a  few  of  the  phenomena 
only,  and  there  our  knowledge  ceases. 

29.  It  is  thought  by  many  of  the  best  observers  and  students  of  magnetism,  that  the 
magnetic  poles  are  moving  in  irregular  paths  about  the  geographical  poles.     This  theory  is 
not  yet  fully  confirmed. 

30.  In  several  countries, magnetic  observatories  have  been  established,  under  the  control 
of  their  respective  governments,  for  the  purpose  of  investigating  the  phenomena,   and 
studying  the  laws  of  magnetism.1 

WHAT  HAS  BEEN  TAUCHT  IN  CHAPTER  YL 


Magnets  are  pieces  of  steel  or  nickel  having 
the  property  of  attracting  other  pieces  of  steel 
and  nickel  or  bits  of  soft  iron. 

Steel  and  nickel  retain  their  magnetism  per- 
manently, while  iron  does  not. 

A  piece  of  steel  accurately  balanced,  and  then 
magnetized,  rests  always  in  a  north-and-south 
position. 

It  no  longer  remains  balanced,  one  end  of  the 
needle  dipping  toward  the  Earth. 

The  end  of  the  needle  pointing  towards  the 
north  is  called  the  north  or  -  pole  ;  the  other,  the 
south  or  +  pole. 

A  mariner9 s  compass  consists  of  a  niagnct 
balanced  and  fastened  to  a  card,  on  which  the 
cardinal  points  are  printed. 

The  compass-needle  never  points  exactly  north 
and  south  except  on  a  certain  irregular  line 
called  the  magnetic  meridian,  or  line  of  no 
declination. 


West  of  this  line,  the  -  end  of  the  needle  points 
east  of  north.  East  of  it,  the  -  end  of  the  needle 
points  west  of  north. 

At  the  magnetic  North  Pole,  the  needle  takes 
a  vertical  position,  the  -  end  down. 

At  the  magnetic  South  Pole,  the  needle  is  also 
vertical,  the  +  end  down. 

Midway  between  the  magnetic  poles,  the  needle 
lies  horizontal. 

These  variations  are  themselves  constantly 
changing. 

The  rate  of  change  is  not  uniform. 

In  every  place,  the  magnetic  needle  has  three 
regular  variations — the  daily t  the  monthly,  and 
the  yearly. 

About  every  eleven  years,  there  occurs  a  period* 
during  which  the  magnetic  needle  *is  subject  to 
unusual  disturbances. 

During  this  period  of  magnetic  storms,  the 
Aurora  Borealis  is  of  frequent  occurrence. 


1  The  United  States  Magnetic  Observatory  is  located  at  Los  Angeles,  California.  It  is  a  low  frame  building,  partly 
underground.  The  walls,  each  a  foot  in  thickness,  are  double,  and  have  a  space  of  three  feet  between  them.  In  the  erection 
of  this  building  no  iron  has  been  used — copper  being  employed  for  all  metal  work. 

In  the  magnet  room  are  three  magnets,  on  which  observations  are  taken.  The  first  of  these,  suspended  by  a  strand 
of  unspun  silk,  is  called  the  vnifilar  magnetometer.  This  instrument  records  variations  in  declination  only.  The  second,  or 
bifilar  magnetometer,  is  suspended  by  two  strands  in  such  a  manner  that  it  is  forced  to  point  east  and  west.  It  is  employed  to 
measure  the  strength  of  the  magnetic  force.  When  this  force  increases,  the  magnet  turns  toward  the  geographical  meridian. 
The  third  magnet,  called  the  vertical  force  or  balance  magnetometer,  is  balanced  on  a  knife  edge,  and  is  used  to  detect  any 
change  of  dip  or  vertical  force.  All  of  these  instruments  rest  on  solid  piers  of  masonry  and  each  is  covered  by  a  glass  globe, 
in  order  to  guard  it  from  possible  disturbance. 

To  each  magnet, a  mirror  is  attached,  before  which  a  lamp  is  placed  in  such  a  manner  that  the  mirror  reflects  a  small 
dot  of  light  upon  a  cylinder  covered  with  photographic  paper.  Now,  if  the  magnet  turns  ever  so  little,  the  dot  of  light 
moves,  and  its  motion  is  recorded  on  the  photographic  paper.  Each  cylinder  revolves  once  in  twenty-four  hours,  and  therefore 
the  swerving  ray  of  light  has  photographed  an  irregular  line  the  whole  length  of  the  paper.  The  amount  of  deviation  of 
this  irregular  line  shows  the  variation  for  every  minute  of  the  day.  Each  magnet  is  provided  with  a  telescope  and  scale, 
in  order  that  readings  may  be  made  independently  of  the  photographic  record. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


CHAPTER 


VO:LCA..NTC     FORCES. 


1.  Definition.  —  Volcanoes  are  openings  in  the 
Earth's  crust,  out  of  which  steam,  various  gases, 
and  molten  rock  or  lava  are  forced.1 

2.  Structure.  —  The  matter   ejected    collects 
about  the  volcanic  opening,  and  builds  up  a  cone- 
shaped  mountain.     At  the  top  of  the  mountain,  is  a 
basin  or  depression,  called  the  crater. 

3.  Volcanic  craters  vary  in  size,  from  a  few 
rods  to  more  than  a  mile  in  diameter.     They  are 
seldom  more  than  four  or  five  hundred    feet    in 
depth,  measuring  from  the  rim  of  the  crater  to  its 
floor.3 

4.  The  floor  of  the  crater  is  the  upper  sur- 
face of  a  solid  plug  of  lava  which  extends  below  to 
an  unknown  depth.     This  plug  is  generally  blown 

crater  of  a  Volcano.  out  in  fragments  whenever  an  eruption  occurs. 

5.  At  the  surface  of  the  crater  floor,  are  sometimes  one  or  more  small  cones  —  really 
miniature  volcanoes  —  which  are  nearly  always  emitting  gases  or  small  quantities  of  lava. 

6.  With  each   succeeding  eruption,  not  only  are  the  form  and  size  of  the  crater 
changed,  but,  owing  to  the  lava,  scoriae,  and  ashes  falling  upon  its  sides,  the  whole  mountain 
is  also  greatly  altered  in  outline  and  appearance. 

7.  The  scoriae  of  volcanoes  consist  of  partly  fused  and  blistered  cinders,  in  appear- 
ance  something  like  the   clinkers  that  form  in  the   grates  of  stoves  burning  soft  coal. 
Volcanic  "  ashes  "  are  not  ashes,  but  matter  which  has  been  finely  divided  or  pulverized  by 
the  eruption. 

8.  Cause  of  Eruption.  —  The  origin  of  the  forces  which  cause  volcanic  eruptions  is  not 
known  with  certainty;  it  is  usually  attributed  to  the  formation  of  steam  from  the  water 
which  finds  a  passage  into  the  hot  reservoirs. 

9.  The  force  required  to  raise  a  column  of  lava  to  the  top  of  Cotopaxi  exceeds  25,000 
Ibs.  per  square  inch.     But  volcanic  forces  have  hurled  rocks  and  steam  from  the  crater  of 
Vesuvius  to  a  height  of  four  miles.     This  force  would  hardly  be  greater  were  the  volcanic 
opening  and  reservoir  beneath  filled  with  gunpowder  and  exploded. 


1  The  subterranean  reservoirs  in  which  the  volcanic  matter  collects,  and  from  which  it  is  ejected,  are  not  situated  at 
a  great  depth  below  the  surface  of  the  Earth.     Such  reservoirs,  while  they  indicate  internal  heat,  have  no  reference  to  the 
"  fluid  interior  "  of  the  Earth. 

2  The  diameter  of  the  crater  of  Vesuvius  has  varied  from  1,000  to  4,000  feet.     That  of  Kilauea,  the  chief  volcano  of 
the  Sandwich  islands,  is  at  present  about  three  miles  long  and  one  mile  wide.     Several  craters  of  lunar  volcanoes  exceed 
50  miles  in  width. 


VOLCANOES    AND     VOLCANIC    FORCES. 


45 


10.  With  such  enormous  forces 
acting  within,   the    crust    of    the 
Earth    yields    at    the    weakest 
place.    But  the  weakest  places  are 
in    mountain    ranges,   where    the 
crust   has   been    already    rent    or 
broken.     Hence  we  find  all  of  the 
volcanoes  of  the  Earth  scattered 
along  the  main  axes  of  mountain 
systems. 

11.  Lines  of  Fissure. — Not 

infrequently,  there  occur  chains  of 
•volcanic  mountains,  all  perhaps 
active,  only  a  few  miles  distant 
from  one  another.  In  such  cases,  it 
seems  probable  that  the  volcanoes 
are  all  situated  on  the  same  rent 
or  fissure.1 

12.  In  at  least  one  instance, 
the  volcanoes  composing  a  chain 
are  connected  by  subterranean 
channels.    Thus  while  Vesuvius 
has   been   active,   Epomeo   (u-po'- 
raa-o),    in    the    island    of    Ischia 
(is'-ke-a),  a  few  miles  distant,  re- 
mains quiet. 

13.  But  when   the  eruptions 
of  Vesuvius  cease,  Epomeo  at 

once  bursts  forth  with  terrible  energy.     During  the  past  2,000  years,  volcanic  activity  has 
passed  back  and  forth  across  the  Phlegrean  (fle'-gre-ari)  Fields,  between  Vesuvius  and  Ischia. 

14.  The  Phlegrean  Fields,  situated  on  the  north  side  of  the  bay  of  Naples,  contain 
about  twenty-five  well  defined  craters.     Two  of  these,  Lake  Avernus  and  the  Lucrine  lake — 
probably  owing  to  subsidence — are  filled  with  water. 

15.  Types  of  Eruption. — A  few  volcanoes  are  constantly  active.     Some,  though  dis- 
charging but  little  lava,  are  always  emitting  great  quantities  of  steam  and  other  vapors. 
Others  again,  remain  quiet  for  centuries,  and  then  burst  forth  with  frightful  energy. 

16.  Stromboli  (strom'-bo-le),  on  one  of  the  Lipari  (lip'-ar-e)  islands,  is  an  example  of 
the  former.     It  is  constantly  ejecting  steam  and  lava,  but  with  so  little  violence  that  one 
may  safely  approach  within  a  few  rods  of  the  crater.     Of  the  latter  class,  Etna  and  Vesu- 
vius are  notable  examples. 

17.  Phenomena  of  Eruption. — When  an  eruption  of  a  volcano  of  the  latter  type 
occurs,  the  floor  of  the  crater  is  first  blown  into  the  air  in  fragments.     At  the  same  time, 
immense  quantities  of  steam  and  gas  are  ejected,  which,  falling  as  a  corrosive  rain,  cause 
greater  destruction  even,  than  the  flood  of  lava  which  follows. 

1  On  the  island  of  Sumatra,  less  than  1,000  miles  long,  there  are  more  than  100  active  volcanic  craters.  In  the  Aleutian 
islands,  there  are  31  active  volcanoes  on  a  line  less  than  500  miles  in  length.  In  Iceland,  there  are  13 ;  in  the  Azores,  6 ;  and 
on  the  peninsula  of  Kamtschatka,  12  volcanic  mountains,  all  showing  signs  of  activity. 


Cotopaxi,  the  highest  Volcano  of  South  America.    Eruption  of  1655. 


46 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Successive  Eruptions  along  the  Line  of  Fissure. 


18.  The  flow  of  lava  begins 
after  the  discharge  of  steam,  being 
at  first  violent,  but  afterwards  steady 
and  quiet.     When  the  reservoir  of 
lava  has  been  exhausted,  the  erup- 
tion gradually  dies  away  with  the  es- 
cape of  gas.1 

19.  Succeeding  eruptions  may 

form  new  craters  along  the  "line  of 

fissure."    Indeed,  it  is  seldom  that  this  does  not  occur  during  violent  eruptions.     The  accom- 
panying figure  shows  the  manner  in  which  these  new  craters  are  formed. 

20.  During  the  eruption  of  Vesuvius,  A.D.  79,  a  new  crater  opening  on  the  side  soon 
built  up  a  mountain  exceeding  Vesuvius  in  height.     One  rampart  of  the  old  crater  has  been 
named  Monte  Summa ;  the  new  cone  is  called  Vesuvius. 

21.  In  volcanoes  constantly  active   like  Stromboli,   the   eruptions,    occurring  at 
intervals  of  from  ten  to  twenty  minutes,  consist  merely  of  a  puff  of  steam  and  other  gases 
forcing  their  way  upward  through  the  lava. 

22.  The  seething  lava  may  be  seen  in  the  crater,  rising  toward  the  top.     At  last,  a 
gigantic  bubble  forms,  and  bursting,  hurls  a  shower  of  molten  lava  into  the  air. 

23.  The  study  of  those  volcanoes  in  and  about  the  Mediterranean  sea  has  contributed 
the  most  reliable  knowledge  concerning  the  phenomena  of  volcanic  outbursts. 

24.  Laws  of  Eruption. — Situated  in  the  most  populous  and  enlightened  centers,  they 
have  been  studied  for  more  than  2,000  years,  and  from  their  records  the  following  conclu- 
sions are  drawn  : — 

An  eruption  following  a  long  period  of  inactivity  is  apt  to  be  violent,  or  else  long  con- 
tinued. 

Feeble  and  short  eruptions  occur  at  much  shorter  intervals  of  time. 

Volcanoes  constantly  active  show  very  feeble  energy. 

Eruptions  are  caused  by  the  accumulations  of  steam  and  gases  under  great  pressure. 

25.  Distribution   of  Volca- 
noes.—  The    number   of    volcanic 
mountains  on  the  Earth  having  well 
defined    craters,  exceeds    1,000 ;    of 
these,  about  350  show  signs  of  ac- 
tivity. Of  the  active  volcanoes,  about 
117  are  situated  on  continents;  the 
remainder  are  on  islands. 


26.   Of  the    whole    number 

of  volcanoes,   fully   nineteen-twen- 

tieths  are  on  the  islands  and  coasts 

of  the  Pacific  ocean.     By  referring 

to  the  chart  of  volcanoes,  a  chain  of  volcanic  mountains  may  be  traced  from  the  southern 

extremity  of  South  America  northward  through  the  Andean  and  Rocky  mountain  systems. 


New  craters  formed  along  the  flank  of  Etna  during  eruption  of  1865. 


Volcanic  gases,  with  the  exception  of  steam,  are  generally  combinations  of  sulphur  and  of  chlorine. 


VOLCANOES    AND     VOLCANIC    FORCES. 


47 


20  lx>neitudeEa«t  60 


Distribution  of  Volcanoes.    Bed  bauds  indicate  lines  of  fissure. 

27.  This  chain  extends  to  Asia  through  the  peninsula  of  Aliaska  and  the  Aleutian 
islands,  and  continues  through  the  chain  of  continental  islands  east  of  Asia. 

28.  A  few  leagues  to  the  northward  of  Australia,  it  is  joined  by  another  great  volcanic 
fissure,  which  underlies  the  islands  of  Sumatra  and  Java,  at  present  the  grand  center  of  vol- 
canic force. 

29.  Notice  also  that  this  great  chain  of  volcanoes  and  volcanic  mountains  incloses  the 
division  of  Oceanica,  every  island,  of  which  is  a  volcano. 

30.  There  are  two  well  defined    volcanic    chains    in    the    Atlantic    ocean.     One 
of  these  extends  from  the  West  Indies  through  the  Lesser  Antilles,  and  contains  abo.ut  50 
well  defined  craters. 

31.  Another  begins  with  the  volcanic  rocks  in  Greenland,  and  passes  southward  through 
Jan  Mayen  (yan-ml'-eri)  island,  Iceland,  the  Azores,  the  Canaries,  and  the  Cape  Verd  islands. 
From  this  chain  a  branch  extends  through  the  Faroe  islands  to  the  north  of  Iceland.     These 
volcanoes  are  situated  in  a  submarine  mountain  range'. 

32.  Another  branch  passes  through  the  Mediterranean  sea.     Etna,  Vesuvius,  Stromboli, 
Graham's  island,  and  a  large  number  of  others,  are  situated  along  this  chain.     They  form 
another  great  center  of  volcanic  activity. 

33.  Utility. — "Volcanoes  are  the  safety  valves  of  the  Earth.''    The  truth  of  this  we  can 
realize  in  studying  the  nature  and  the  greatness  of  the  forces  constantly  at  work  within  the 
Earth's  crust. 

34.  Were  it  not  for  these  natural  channels  for  the  escape  of  pent-up  forces,  the  crust  of 
the  Earth  would  be  constantly  in  a  state  of  convulsion. 


48  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 

35.  Earthquakes  frequently  precede  volcanic  outbursts,  and  are  often  their  only 
warning.     Indeed,  it  is  not  improbable  that  the  same  forces  which  cause  the  latter  are  also 
the  cause  of  the  former. 

36.  Occurrence. — The  most  notable  as  well  as  the  most  destructive  volcanic  eruptions 
of  which  there  is  any  record,  have  occurred  among  the  Mediterranean  and  the  Javanese 
groups.     Of  the  first  group,  Vesuvius  has  been  always  the  chief  actor.1 

37.  In  1538,  an  eruption  occurred  in  the  Phlegrean  Fields,  soon  building  a  mountain  to 
the  height  of  500  feet.     This  cone  was  named  Monte  Nuovo. 

38.  In  the  same  year,  Graham's  island,  a  volcano  off  the  coast  of  Sicily,  was  lifted  above 
the  sea.     During  its  short  existence,  its  eruption  was  very  violent,  lava  being  thrown  to  a 
height  of  200  feet.     When  the  eruption  ceased,  the  island  began  to  sink,  and  within  two 
years  had  wholly  disappeared. 

39.  The  most  terrible  eruptions  have  occurred  in  the  Javanese  group.     The  Javanese 
records  mention  an  outburst  in  the  12th  century,  during  which  Java  and  Sumatra,  then  a 
single  island,  were  separated  and  the  strait  of  Sunda  formed  between  them.     The  small 
"volcanic  island  Krakatu,  remained  above  the  ocean  level,  however,  and  has  shown  more  or 
less  activity  ever  since.2 

1  Prior  to  A.D.  79,  no  eruptions  of  Vesuvius  had  been  recorded.  The  cities  of  Stabiae,  Herculaneum,  and  Pompeii 
(pom-pay1  e)  had  been  built  at  its  base,  and  gardens  and  vineyards  covered  its  sides  nearly  to  the  ramparts  of  the  crater.  In 
A.D.  63,  a  violent  earthquake  occurred  which  overthrew  many  buildings,  causing  considerable  loss  of  life  and  destruction  of 
property.  The  alarm  consequent  upon  this  disaster  soon  subsided,  and  for  sixteen  years  there  was  nothing  to  arouse  the 
fears  of  the  people  dwelling  within  the  doomed  cities. 

On  the  24th  of  August,  A.D.  79,  a  column  of  dense  smoke  (volcanic  ashes)  was  observed  rising  from  the  top  of  the 
"mountain.  The  elder  Pliny,  then  in  command  of  the  Roman  fleet,  desirous  of  learning  the  cause  of  the  extraordinary  occur- 
rence, landed  at  Stabise  and  hastened  at  once  to  the  villa  of  his  friend  Pomponius.  As  night  came  on,  streaks  of  fire  appeared 
on  the  sides  of  the  mountain,  and  simultaneously  with  the  darkening,  showers  of  ashes,  stones,  and  rain  began  to  fall 
thick  and  fast. 

Perceiving  that  the  villa  would  be  soon  destroyed,  Pliny  and  his  friend,  with  their  servants,  endeavored  to  make  their 
•way  to  the  harbor.  Tying  pillows  on  their  heads  to  shield  them  from  the  increasing  shower  of  stones,  they  attempted  to 
Teach  the  sea  shore,  hoping  to  regain  the  nearest  vessel  of  the  fleet.  Before  they  had  reached  a  place  of  safety,  however, 
Pliny,  overcome  by  stifling  vapors,  fell  to  the  ground  dead. 

Morning  dawned  in  the  blackness  of  midnight.  The  air  was  still  thick  with  falling  ashes  and  loaded  with  sulphurous 
vapors.  When,  at  last, light  was  restored,  a  scene  of  inconceivable  desolation  appeared.  The  cities  of  Stabiae,  Herculaneum, 
and  Pompeii,  as  well  as  the  beautiful  villas  and  gardens  dotting  the  mountain  side,  had  disappeared — all  buried  with  their 
inhabitants  beneath  the  fallen  ashes.  For  more  than  1,600  years  not  a  vestige  of  the  ill-fated  cities  was  found.  In  1753, 
some  workmen  digging  a  well  came  upon  a  building  which  proved  to  be  a  theatre  of  Herculaneum.  Since  that  time  a  large 
part  of  the  city  of  Pompeii  has  been  uncovered.  From  appearances,  it  seems  probable  the  fatal  shower  occurred  sq  suddenly 
that  many  of  the  inhabitants  perished  in  their  houses. 

After  this  eruption,  Vesuvius  remained  quiet  for  over  100  years.  Since  that  time,  about  twenty  eruptions  have  taken 
place,  the  last  occurring  in  1872.  Professor  Palmieri,  who  remained  in  his  observatory  on  the  side  of  the  mountain  during 
this  eruption,  describes  the  spectacle  as  "  seeming  as  though  the  mountain  were  sweating  fire  at  every  pore."  In  all  former 
•eruptions  of  Vesuvius,  little  else  besides  ashes  was  ejected.  Later  ones  have  been  marked  by  the  ejection  of  immense  quan- 
tities of  lava. 

8  In  August,  1883,  "  without  any  warning  there  was  an  outburst,  and  Krakatu  vomited  an  ink-black  cloud  which  soon 
involved  the  land  in  complete  darkness.  Then  it  began  to  rain  scoriae  and  dust,  and  in  a  Very  few  minutes, the  greater  part 
•of  northern  Bantam,  a  fertile  and  populous  country,  was  destroyed.  Tremendous  explosions  hurled  volcanic  matter  to  a 
•distance  of  many  miles ;  the  sides  of  the  volcano  were  blown  into  the  sea,  its  structure  collapsed,  and  the  entire  island  slowly 
subsided.  On  the  following  morning,  only  half  of  the  island  was  above  the  water's  level."  More  than  100,000  people  perished 
fcy  this  convulsion. 

Iceland  contains  thirteen  volcanoes,  of  which  Hecla  and  Skaptar  Jokul  are  the  most  noted.  During  an  eruption  of  the 
latter  in  1873,  the  lava  ejected  formed  a  stream  50  miles  long,  having  an  average  breadth  of  15  miles. 


VOLCANOES    AND     VOLCANIC    FORCES. 


49 


40.  There  have  been  several  eruptions  of  Etna. 
The  most  destructive  occurred  in  1669,  during  which 
Catania  was  destroyed  by  the  lava  flood.     Cotopaxi 
in  South  America,  and  Kilauea  in  the  Sandwich 
islands  are  celebrated  for  their  violent  outbursts.1 

41.  Mud   Volcanoes.  —  Mud   volcanoes   and 
geysers  are  both  forms  of  volcanic  energy,  each 
being  caused  by  subterranean  heat.    Except  in  the 
magnitude  of  their  eruptions,  they  do  not  differ 
greatly  from  volcanoes. 

42.  Geysers. — Geysers  are  hot  springs  occur- 
ring in  volcanic  regions.    At  regular  intervals, there 
is  a  gentle  overflow  of  water  at  the  surface  ;  then  a 
column  of  water  is  shot  high  into  the  air  ;  and  lastly, 
steam  under  great  pressure  escapes  with  a  roar  that 
may  be  heard  for  miles. 

43.  The  geyser  differs  from  other  hot  springs 
only  in  having  an  irregular,  long  tube  reaching 
deep  into  the  heated  rocks. 

44.  Structure.  —  The  geyser  itself  builds  this 
tube  from  the  silica,  of  which  sand  is  a  familiar  ex- 
ample, which  its  waters  dissolve  while  they  are  hot, 
and  again  deposit  around  the  spring  on  cooling.2 

45.  Phenomena  of  Eruption. — The  water  in 
the  bottom  of  this  tube  may  be  heated  many  degrees 

higher  than  the  boiling  point  of  water,  but  because  Geyser  m  Yellowstone  Park. 

the  pressure  above  is  so  great,  the  water  cannot  boil  and  hence  steam  cannot  form. 

46.  By  and  by,  the  water  in  the  center,  or  perhaps  near  the  top  of  the  tube,  becomes 
so  hot  that  great  bubbles  of  steam  form  and  force  some  of  the  water  out  at  the  top  of  the 
spring. 

47.  As  soon  as  this  takes  place,  the  pressure  at  the  lower  part  of  the  tube  is  removed, 
and  the  water, heated  so  far  above  boiling  point, at  once  flashes  into  steam.    This  it  does — 
not  gradually,  but  instantly — and  the  force  of  the  escaping  steam  throws  a  column  of  hot 
water  often  200  feet  or  more  into  the  air. 

48.  There  are  three  regions  where  geysers  chiefly  occur.    Iceland,  New  Zealand, 
and  the  Yellowstone  Park  northwest  of  Wyoming.      The  last,  by  far  the  most  extensive, 
contains  about  10,000  mud  volcanoes,  geysers,  and  hot  springs. 

49.  The  geysers  of  the  Firehole  river  in  this  park  are  the  most  wonderful  in  the 
world.     "  The  geyser  basin  is  covered  with  snowy  crystals  of  alkali  and  silica,  often  forming 
the  most  exquisite  and  fantastic  designs."3 

v ' 

1  During  1883,  Bogosloff,  one  of  the  Aleutian  islands  near  Unalashka,  and  St.  Augustin  in  Cook's  Inlet — both  volcanic 
islands  near  Alaska — were  rent  by  terrible  eruptions.     The  former  was  leveled  nearly  to  the  water's  edge ;  the  latter  was 
split  in  twain. 

2  Hot  alkaline  waters  only  will  dissolve  sand.     Bunsen  found  the  waters  of  all  the  Iceland  geysers  to  be  alkaline,  and 
that  none  but  alkaline  springs  were  eruptive. 

8  "  In  some  places,  the  silica  is  deposited  in  a  gelatinous  condition  to  a  depth  of  three  or  four  inches.     Trunks  and 
branches  of  trees  immersed  in  these  waters  are  quickly  petrified." — Le  Conte. 


50 


MONTEITH  S    NEW    PHYSICAL     GEOGRAPHY. 


50.  There  are  seventy-one  geysers  in  this  region,  from  six  of  which  the  water  is  thrown 
to  a  height  exceeding  150  feet. 

51.  The  Iceland  region  contains  about  100  geysers,  of  which  the  Great  Geyser  is  the 
best  known.     Its  eruptions  occur  regularly  at  intervals  of  an  hour  and  a  half,  throwing  a 
column  of  water  eighteen  feet  in  diameter  to  a  height  of  one  hundred  feet.1 

52.  The  crater  or  basin  of  the  Great  Geyser  is  more  than  fifty  feet  in  diameter,  and  the 
surrounding  wall  is  thirty  feet  in  height.     The  tube  is  eighteen  feet  in  diameter  and  extends 
to  a  depth  of  eighty  feet. 


WHAT  HAS  BEEH  TAUGHT  IN  CHAPTER  YIL 


Volcanoes  are  channels  opening  from,  the  in- 
terior to  the  surface  of  the  Earth. 

Out  of  this  opening,  molten  rock  or  lava,  hot 
gases,  steam,  and  water  are  forced. 

The  substances  ejected  from,  the  volcano  build 
up  a  cone-shaped  mountain  about  the  opening, 
forming  at  the  top  a  cup-like  depression, called 
the  crater. 

With  every  eruption,  not  only  is  the  size,  posi- 
tion, and  shape  of  the  crater  greatly  changed,  but 
often  the  whole  mountain  is  changed  in  appear- 
ance. 

The  origin  of  volcanic  forces  is  generally  as- 
cribed to  the  pressure  of  steam  and  other  gases 
within  the  Earth. 

The  enormous  pressure  developed  causes  the 
crust  of  the  Earth  to  give  way  at  the  weakest 
poini ,  which  is  along  the  axis  of  a  mountain 
system. 

Volcanoes  situated  on  the  same  range  are  fre- 
quently connected  by  subterranean  channels,  and 
the  eruption  often  travels  along  the  fissure  formed 
by  the  broken  crust. 

Volcanoes  are  always  situated  near  the  sea 
coast. 

The  average  volcanic  eruption  consists  of:  1st, 
the  blowing  out  of  the  crater  floor  and  the  dis- 
charge of  steam,  water,  etc.  ;  2nd,  the  discharge 
of  lava ;  3rd,  the  escape  of  gases. 

When  volcanoes  are  constantly  active,  the 
eruptions  are  not  violent. 


The  most  violent  eruptions  occur  after  long 
periods  of  inactivity. 

About  35O  volcanoes  are  known  to  be  active, 
117  of  which  are  on  continental  lands.  The 
remaining  233  are  on  islands. 

The  most  remarkable  chain  of  volcanoes  skirts 
the  shores  of  the  Pacific  ocean,  inclosing  the  divi- 
sion, of  Oceanica,  every  island  of  which  is  a  vol- 
cano. 

A  chain  of  submerged  volcanoes  extends 
through  the  Atlantic  ocean  from  Jan  Mayen 
island,  one  branch  of  which  extends  eastward 
through  the  Mediterranean  sea. 

Mud  volcanoes  and  geysers  are  forms  of  vol- 
canic action,  differing  from  volcanoes  only  in 
magnitude  and  violence. 

TJie  material  ejected  from  geysers  is  always 
hot  water,  and  the  eruptions  take  place  at  reg- 
ular intervals. 

The  water  of  geysers  being  alkaline,  dissolves 
silica  or  sand.  In  cooling,  the  tvater  again  de- 
posits the  silica  which  it  had  dissolved. 

The  silica  thus  deposited  finally  builds  an  ir- 
regular tube,  extending  from  the  source  of  heat 
beneath  to  the  surface  of  the  Earth. 

The  eruption  of  the  geyser  is  due  to  the  sud- 
den formation  of  steam  from  water  that  has 
been  heated  above  the  boiling  point. 

The  principal  geyser  regions  of  the  world  are 
the  Yellowstone  Park  in  the  United  States,  and 
Iceland. 


1  There  is  a  small  geyser  region  in  the  Malheur  valley,  in  eastern  Oregon.  They  are  true  spouting  geysers,  but  are 
insignificant  in  size  and  few  in  number.  The  geysers  of  Sonoma  county,  California,  are  not  true  geysers,  but  boiling  mineral 
springs.  They  are  not  eruptive. 


EARTHQ  UAKES. 


51 


CHAPTER 

EARTHQUAKES. 

1.  Physical  Phenomena. — Earthquakes  are  tremblings  or  vibrations  of   some  part 
of  the  Earth's  crust.     They  are  often  connected  with  volcanic  action,  and  it  seems  highly 
probable  that  both  are  caused  by  the  same  forces. 

2.  Volcanic  outbursts  are  nearly  always  preceded   by  earthquakes,   which  cease 
after  the  eruption  has  occurred.     The  stoppage  of  volcanic  action  is  frequently  followed 
by  disastrous  earth-shocks. 

3.  When  the  smoke  from  Cotopaxi  ceases  to  appear,  the  people  of  Quito  (kee-to)  are 
always  in  great  dread  of  earthquakes.     During  the  intervals  when  Vesuvius  and  Epomeo 
are  both  quiet,  the  surrounding  country  is  subject  to  violent  shocks. 

4.  Earthquakes   sometimes   occur  in  regions   remote   from   all   volcanic    centers. 

These  are  undoubtedly  brought  about  by  the  rising,  the  sinking,  or  by  other  movements 
of  large  masses  of  the  Earth's  crust.1 

5.  Causes. — The  cause  of  earthquakes  of  the  first  type  is  attributed  to  the  explosive 
formation  of  large  volumes  of  steam  or  other  gases  in  the  hot  interior  of  the   Earth. 
Except  in  the  magnitude  of  their  effect,  such  earthquakes  are  not  unlike  the  jar  following 
the  explosion  of  a  great  quantity  of  gunpowder. 

G.  Earthquakes  of  the  second  class  are  attributed  to  the  gradual  contraction  of  the 
Earth's  interior,  in  cooling.  The  shrinkage  of  the  heated  interior  is  much  greater  than  that 
of  the  overlying  crust. 

7.  If  the  crust  yields,  the  shrink- 
age will  be  gradual  and  unnoticed ; 
but  if  it  resists,  by  and  by  the  increas- 
ing force  becomes  great  enough  to 
break  or  crush  the  resisting  parts. 

8.  Such  a  breaking  or  crushing" 
of  large  masses  of  earth  is  sufficient 
to  produce  the  jarring  or  trembling 
that  constitutes  an  earthquake. 

9.  Analysis   of  Shock,  —  If  a 

Stone  be  flung   into    the  Water,  Waves  ..  FaaU8,  causea  by  the  Sinking  of  Broken  Strata. 

are  produced  precisely  like  those  of 

the  ground  during  an  earthquake.  At  the  spot  where  the  stone  strikes,  the  motion  of  the 
water  is  up-and-ddwn.  This  movement  makes  a  great  number  of  circular  waves,  one 
outside  of  the  other,  which  spread  over  a  large  surface. 

1  The  coast  of  Chili  was  elevated  from  two  to  ten  feet  during  an  earthquake  in  1835.  An  area  of  land  exceeding 
2,000  square  miles  in  extent,  lying  near  the  mouth  of  the  Indus,  was  wholly  submerged  by  nn  earthquake  occurring  in  the 
North  Indian  ocean.  During  a  severe  earthquake,  which  in  1811  occurred  in  the  Mississippi  valley,  several  large  bodies  of 
land  near  the  mouth  of  the  Ohio  river,  sunk,  and  to  this  day  remain  covered  with  water. 


52  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 

10.  Above  the  center  of  the  concentric  circles,  the  motion  consists  of  up-and-down 
vibrations,  but  at  all  other  places  on  the  surface,  it  gradually  acquires  a  "rocking"  motion. 
In  the  following  diagram,  it  is  shown  how  the  vibrations  of  the  earth-wave  may  differ  in 
quality  in  different  places. 

4 5 5 o       E        p 


Diagram  to  Illustrate  the  Motion  and  Direction  of  Earthquake-waves. 


11.  For  instance,  the  shock  may  have  originated  at  O,  the  focus  of  the  earthquake, 
some  distance  below  the  surface.     When  the  waves  reach  the  surface  at  A,  directly  above 
O,  the  vibrations  are  vertical,  and  are  known  as  explosive  or  vertical  waves.     Waves  of 
this  character  are  very  destructive. 

12.  At  some  distance  from  A,  as  E,  F,  and  G,  the  waves  will  no  longer  be  up-and- 
down  ;  they  will  travel  along  the  surface  as  rocking  waves.     These  are  called  "horizontal 
waves  of  progression,"  or  spreading  surface  waves.     At  a  short  distance  from  a  point  over 
the  focus  of  the  earthshock-waves,  as  at  B  or  C,  the  waves  partake  of  both  the  rolling  and 
the  vertical  motion.     Here  the  destructive  effects  are  by  far  the  greatest. 

13.  In  a  few  instances,  the  ground  has  been  twisted  or  whirled  around,  and  buildings 
have  been  turned  so  as  to  face  in  an  opposite  direction.     Earthquakes  of  this  kind  are 
very  rare ;  they  are  usually  known  as  vorticose,  or  whirling  shocks,  and  are  even  more 
destructive  than  vertical  waves. 

14.  Velocity  of  Wave.  —  The  velocity  of  earth-waves  varies,  being  much  greater  in 
hard  than  in  loosely  cohering  rock.      Careful  experiments  indicate  an  average  of  about 
nineteen  miles  a  minute. 

15.  Attending  Phenomena.— Subterranean  sounds  occasionally  precede  earthquakes. 
Sometimes,  these  sounds  are  like  the  roll  of  heavy  wagons  on  the  pavement ;  sometimes,  like 
the  sharp  reports  of  cannonading ;  and  now  and  then,  it  resembles  the  crunching  together 
of  rough  surfaces  of  rock  under  immense  pressure. 

16.  Occurrence.— According  to  Alexis  Perrey,  an  average  of  nearly  600  earthquakes 
happen  yearly.      This  number  includes  all   earth-tremblings  —  even  those  imperceptible 
without  the  aid  of  instruments.      It  is  plain,  therefore,  that  in  some  part  or  other  the 
Earth's  crust  is  constantly  quaking. 


EARTHQUAKES, 


53 


17.  Because  earth- 
quakes are   most   fre- 
quent   in   winter    and 
at  full   moon,  it    is 
thought    that    the    at- 
tractive forces  of   the 
sun  and  the  moon  in- 
crease the  strain  on  the 
Earth's  crust,  produc- 
ing greater  frequency 
of  shocks. 

18.  Distribu- 
tion. —  Although 
earthquakes    occur   in 
all  parts  of  the  world, 
they  are  most  frequent 
in  volcanic  countries, 
and  along   the   more 
recently  formed 
mountain  ranges. 

19.  The  regions  in 
which  earthquakes  are 
most  prevalent   corre- 
spond closely  to  those 
of  volcanic  formation. 
The    principal     earth- 
quake region  of  North 
America  is  on  the  Pa- 
cific   coast,  California 
especially   being    sub- 
ject to  frequent  shocks, 
sionally  shaken. 

20.  Areas,  of  Elevation  and  Subsidence. — There  are  also  changes  of  level  in  the 
Earth's  crust  which  take  place  so  gradually  as  to  be  imperceptible,  except  in  long  intervals 
of  time.     For  instance  :— 

The  eastern  coast  of  Greenland  is  slowly  sinking. 
The  coast  of  North  America,  in  the  region  of  Labrador,  is  rising1. 
The  northern  part  of  Norway  and  Sweden  is  rising  at  the  rate  of  six  feet  per 
century. 

The  coast  of  Florida  is  slowly  sinking. 

The  bed  of  the  Pacific  ocean  in  the  region  of  Oceanica  is  sinking1. 

Memorable  Earthquakes. — The  earthquake  at  Eiobamba,  in  1797,  was  a  striking  example  of  both  vertical 
and  whirling  shocks.  The  city  was  directly  over  the  earthquake  focus,  and  the  earth-wave  was  fully  twelve  feet  in  height. 
Houses  were  thrown  into  the  air,  and  the  bodies  of  some  of  the  victims  were  hurled  to  a  height  of  a  hundred  feet  across 
the  river.  Although  the  shock  lasted  a  few  seconds  only,  nothing  but  heaps  of  stones  were  left  of  a  once  beautiful  city. 
Mbre  than  40,000  people  perished. 

The  Lisbon  earthquake  of  1755  was  frightfully  destructive  of  life  and  property.  At  the  moment  of  the  first  shock, 
most  of  the  buildings  were  overthrown.  The  cathedrals  were  crowded  with  people,  who  had  gathered  there  to  witness  the 


The  Earthquake  at  Arica  and  the  Tidal  Wave  following. 

The  Atlantic  slope  and  the  Mississippi  valley,  however,  are  occa- 


MONTEITITS    NEW    PHYSICAL     GEOGRAPHY. 


Fort  Sindree  before  it  was  submerged  by  the  Earthquake  of  1819. 


ceremonies  of  All  Saints  Day.     Here  the  loss  of  life  was  appalling.     Multitudes  made  their  way  to  the  sea  shore,  hoping 

to  flee  from  the  crash  of  falling  buildings ;  but  an  immense  tidal  wave,  ninety  feet  in  height,  rolled  in  upon  the  shore  and 

engulfed  thousands  whom  the  crash  of  the  city  had  spared.     Throngs  had  sought  refuge  on  the  new  marble  quay  (ke),  but 

scarcely  had  they  reached  it,  before  the  quay  and 
all  who  were  on  it  sunk  beneath  the  waters.  The 
loss  of  life  in  this  catastrophe  exceeded  60,000 
persons. 

In  1868,  there  were  a  great  number  of  violent 
earthquakes  within  the  Pacific  volcanic  belt. 
South  America,  the  Sandwich  islands,  and  Cali- 
fornia, were  all  more  or  less  disturbed.  On  the 
coast  of  Peru,  the  cities  of  Tacua,  Iquique  (e-ke'ka), 
Arequipa  (ah-ra-ke'pa?i),  and  Arica  (afi-re'kah),  were 
destroyed.  In  Ecuador,  the  town  of  Cotocachi 
(ko-to-ka!  che),  sank  out  of  view,  and  a  lake  of  great 
depth  now  covers  its  site. 

The '  Calabrian  earthquakes,  during  which  so 
many  Italian  towns  and  villages  were  destroyed, 
seem  to  have  been  caused  by  the  stoppage  of 
Stromboli,  as  they  promptly  ceased  when  that 
volcano  resumed  activity.  At  the  time  of  these 
earthquakes,  several  towns  and  villages  entirely 
disappeared,  being  engulfed  within  the  earth. 
Near  Terranova,  a  chasm  opened  into  which  a 
part  of  the  town  fell  to  a  distance  of  300  feet. 

Throughout  the  whole  Com  partamente1  the  earth  was  greatly  shaken.     Great  land-slides  occurred;   deep  chasms  opened; 

mud  volcanoes  and  hot  springs  were  formed  ;  and  in  various  places,  bodies  of  land  sank,  the  depressions  being  immediately 

filled  with  water. 

In  1819,  an  area  of  2,000  square  miles  about  the  mouth  of  the  Indus,  in  Hindoostan,  was  suddenly  converted,  by  an 

earthquake,  into  an  inland  sea.      The  fort  and  village  of  Sindree  sank  so  much  that  only  the  tops  of  the  fort,  houses, 

and  trees  remained  above  the  water. 

Ou  the  28th  of  July,  1883,  a  destructive  earthquake  occurred  on  the  island  of  Ischia,  in  the  Bay  of  Naples.     The 

eastern  part  of  the  island,  which  is  almost  wholly 

built  up  by  the  lava  from  Epomeo,  was  fche  center 

of   an   earthshock  which   destroyed  three  towns. 

At  Casamicciola,  where  the  earth-waves  were  ver- 
tical,  the    shock  was   severest.       The   town  was 

totally  destroyed  and  7,000  people  perished. 

A  mild    shock    occurred   August   10,    1884, 

which  involved  the  New  England  and  the  Middle 

States,  reaching  as  far  west  as  Cleveland,  Ohio. 

On  Manhattan  island,2  the  shock  was  vertical. 

There  are  traditions  among  all  peoples  and 

in  every  language,  of  earthquakes  that  have  been 

attended  with  the  rising  or  the  sinking  of  large 

areas  of  land.     The  Indians  of  the  old  San  Fran- 
cisco Mission  believe  that  San  Francisco  Bay  was 

once  high  above  the  water  level,  and  sank  during- 

an  earthquake.     There  is  one  legend  of  this  kind, 

the   story  of  Atlantis,  that  has  more   than  ordi- 
nary interest.      According  to   Plato,  Atlantis  was 

an  island  in  the  Atlantic  ocean,  opposite  to  the 

strait   of  Gibraltar.     "It  was   the  birth-place   of 

civilization   and   the    home    of  a  mighty  nation, 

whose  people  colonized  all  of  the  adjoining  country.     But  in  time,  there  came  a  great  convulsion  of  nature,  and  Atlantis 

with  its  people  sank  into  the  ocean."      It  was  the  original  seat  of  the  Aryan  or  Indo-European  family  of  nations,   the- 

Semitic  and  the  Turanian  races.     Ancient  Egypt,  it  is  asserted,  was  the  oldest  colony  formed  by  the  Atlanteans,  and  from. 

Atlantis,  the  Egyptians  derived  their  civilization. 


Forl  Sindree  after  the  Earthquake. 


District. 


Part  of  New  York  City. 


EARTHQ  UAKES. 


55 


21.  The    Tidal   Wave.- 

Tidal  waves  always  follow  earth- 
quakes that  originate  near  the 
ocean.  These  waves,  however, 
must  not  be  confused  with  the  daily 
tides,  with  which  they  have  no  con- 
nection. 

22.  The  tidal  waves  accompa- 
nying the  Lisbon  earthquake  were 
ninety  feet  high  when  they  broke 
upon  the  shore.     Everything  within 
their  reach  was  destroyed. 

23.  After    the    earthquake    at 
Arica,  Peru,  tidal  waves  sixty  feet 
in  height  rolled  in  for  several  hours, 
destroying    everything    the    earth- 
shock  had  left.      A  United  States 

iron-clad  vessel  was  carried  from  the  harbor  and  stranded  upon  the  beach  two  miles 
from  the  shore.  In  several  other  instances,  vessels  at  anchor  have  been  tossed  upon  the 
shore  and  left  hopeless  wrecks. 

24.  The  tidal  wave  is,  without  doubt,  due  to  the  up-and-down  motion  of  the  ground 
just  above  the  focus  of  the  earthquake.     The  wave  following  the  earthquake  at  Anca 
traveled  across  the  Pacific  ocean,  and  in  fourteen  hours  reached  Japan,  10,000  miles  distant. 


Fissures  formed  during  the  Calabrian  Earthquakes. 


WHAT  HAS  BEEN  TAUGHT  IN  CHAPTER  YIIL 


'Earthquakes  are  vibrations  of  some  parts  of 
the  Earth's  crust. 

In  most  instances,  severe  earthquakes  are 
connected  with  volcanic  action,  usually  preced- 
ing it,  and  ceasing  when  the  eruption  has  fin- 
ished. 

Earthquakes  which  occur  in  regions  distant 
from  volcanic  activity  are  due  to  the  gradual 
shrinkage  of  the  Earth's  crust  in  cooling. 

The  eartJishocfc  itself  consists  of  a  series  of 
waves  originating  at  a  center,  and  radiating 
in  every  direction. 

The  eartJi-waves  thus  formed  possess  differ- 
ent qualities  at  different  distances  'from  the 
center. 

Over  the  center  of  disturbance  the  motion  is 
vertical.  As  the  distance  from  the  center  of 
disturbance  increases,  the  vertical  gradually 
changes  to  a  horizontal  wave. 


In  several  instances,  whirling  shocks  have 
b^en  noticed. 

The  velocity  of  the  wave  varies  from  2,OOO 
to  12,OOO  feet  per  second. 

Eartliquakes  occur  with  greatest  frequency 
in  volcanic  regions,  and  along  newly-formed 
mountain  ranges. 

They  are  most  frequent  during  winter  months 
at  time  of  full  moon. 

TJiere  are  other  changes  of  level  in  the  Earth's- 
crust,  so  gradual  as  to  be  noticed  only  in  long 
intervals  of  time. 

Parts  of  Greenland,  of  Florida,  and  nearly 
the  whole  of  Oceanica  are  sinking;  while  por- 
tions of  Labrador,  Norway,  and  Sweden  are 
rising. 

Ocean  waves  of  great  height,  called  tidal 
waves,  frequently  follow  earthquakes,,  which 
occur  near,  or  In  the  ocean. 


56  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


THE     WALTER     OF     THE     ^TJVEO  SPHERE 


1.  Erosive  Action. — 

Water,  more  than  any  other 

agent  in  nature,  has  worn  The  Water  of  the  Almo8phere. 

and  sculptured  the  surface 

of  the  land,  and  given  to  it  its  present  diversified  appearance  and  picturesque  beauty. 

2.  The  hills  have  had  their  tops  rounded  off,  and  the  plains  and  valleys  have  been 
formed  and  smoothed  over  by  water. 

3.  Those  vast  prairies  of  the  Mississippi  valley  were  made  by  the  water  of  running 
streams,  which  brought  the  material  from  the  Rocky  and  the  Appalachian  mountains  to  fill 
the  ravines  and  level  off  the  rugged  surfaces. 

4.  All  of  those  immense  deposits  of  sedimentary  rock,  sometimes  measuring  miles  in 
thickness,  have  been  worn  away  from  older  rock, '  pulverized,  and  distributed  over  the 
Earth's  surface  by  water. 

5.  Composition. — "Water  is  composed  of  two  gases,  hydrogen  and  oxygen,  combined 
in  the  proportion  of  two  volumes  of  the  former  to  one  of  the  latter.     It  freely  absorbs  air 
and  other  gases,  and  likewise  dissolves  .many  of  the  minerals  of  the  Earth  with  which  it 
comes  in  contact.1 

1  The  oxygen  weighs  eight  times  as  much  as  the  hydrogen. 


THE     WATER     OF    THE    ATMOSPHERE.  57 

6.  Forms    of  Water.  —  At    ordinary  temperatures, 

pure  water  is  a  colorless,  tasteless  liquid.     At  32°  F.,  it  f 

becomes  a  solid,  or  freezes ;  and  at  212°  F.,  it  changes  to 

steam.1 

7.  Expansion.  —  The  bulk  or  volume  of  water  is 
changed  by  heat.     At  39°  F.  a  pound  of  water  occupies  less 
space  than  at  any  other  temperature ;  but  as  the  tempera- 
ture lowers  to  the  freezing  point,  the  volume  increases  very 
slightly — about  one  part  in  400. 

8.  At  the  moment  of  freezing,  the  bulk  increases  about 
one-fourteenth.     The  expansive  force  of  freezing  water  is 

irresistible.     Iron  shells  having  walls  an  inch  thick  have      Expansion  of  water  at  the  moment  of  freezing. 
been  burst  by  freezing  the  water  with  which  they  were  filled. 

9.  Above  39°  F.,  the  bulk  of  the  water  also  increases  with  the  temperature.     Thus,  if 
100  gallons  of  water  at  39°  F.  be  heated  to  the  boiling  point,  it  will  then  measure  nearly 
110  gallons. 

10.  As  water  at  the  freezing  point  is  lighter,  bulk  for  bulk,  than  at  39°  F.,  it  is  plain  that 
when  the  temperature  approaches  the  freezing  point,  that  part  of  the  water  below  39°  F.  will 
rise,  and  the  ice  will  form  on  the  surface  of  the  water  instead  of  at  the  bottom.2 

11.  Specific  Heat. — No  other  element  on  the  Earth  requires  so  much  heat  as  water  to 
warm  it.     The  heat  is  slowly  absorbed,  and  as  slowly  given  out  again.    It  follows,  therefore, 
that  all  large  bodies  of  water  store  up  much  of  the  sun's  heat  during  summer  and  give  it  out 
in  winter,  thereby  tempering  the  climate  of  both  seasons. 

12.  The  heat  required  to  warm  a  pound  of  water  from  32°  F.  to  212°  F.  would  warm 
more  than  nine  pounds  of  iron  to  the  same  temperature. 

13.  Latent  Heat. — Whenever  ice  is  melted  a  certain  amount  of  heat  is  absorbed.     For 
instance,  if  a  vessel  filled  with  ice  at  32°  F.  be  placed  upon  the  fire,  the  temperature  of  the 
water  will  not  rise  above  32°  F.  until  all  the  ice  has  been  melted.    A  large  amount  of  heat  has 
disappeared,  having  been  used  in  melting  the  ice.     If  the  water  be  changed  back  to  ice  all 
of  the  heat  again  appears.3 

14.  Utility. — Without  water,  such  forms  of  life  as  now  dwell  on  the  Earth  could  not 
possibly  exist.     Our  bodies  are  three-fourths  water  ;  the  food  we  eat  is  four-fifths  water  ;  the 
fruits  of  the  tree  and  the  vine  are  nine-tenths  water.     For  many  reasons,  therefore,  a  wide 
distribution  of  water  is  necessary  to  the  growth  and  prosperity  of  a  people. 

1  At  all  temperatures,  to  a  certain  extent,  water  turns  to  vapor.  Even  ice  and  snow  evaporate,  if  the  air  be  dry.  The 
amount  of  water  which  air  can  thus  hold  in  the  form  of  vapor  will  be  shown  in  another  lesson. 

"  Ice  forms  only  at  the  top,  the  mass  of  water  remaining  at  39°  F.  Had  water  become  heavier  as  it  cooled  down  to 
the  freezing  point,  a  continual  circulation  would  be  kept  up  until  the  whole  mass  was  cooled  down  to  32°  F.,  when  solidifi- 
cation of  the  whole  would  ensue.  Thus  our  lakes  and  rivers  would  be  converted  into  solid  masses  of  ice  which  the  summer's 
warmth  would  be  insufficient  to  melt ;  and  hence,  the  climate  of  our  now  temperate  zone  might  approach  in  severity  that 
of  the  Arctic  regions." — Roscoe. 

8  When  water  boils,  no  matter  how  fierce  the  heat,  the  temperature  remains  at  212'  F.  until  the  whole  of  the  water 
has  evaporated.  This  is  because  the  heat  has  been  used  to  change  the  water  to  steam.  But  when  the  steam  is  again  con. 
verted  to  water,  all  the  heat  is  set  free. 


58 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


15.  Atmospheric  Water. — Every  drop  of  water  on  the  land,  whether  in  wells  or  springs, 
lakes  or  rivers,  has  been  brought  from  the  ocean  by  the  winds,  which,  taking  it  up  in  the 
form  of  vapor,  pour  it  upon  the  land  as  rain.     Let  us  learn  the  way  in  which  this  takes 
place. 

16.  Air  has  the  property  of  taking  up  water  in  the  form  of  vapor.    We  may  notice  that 
after  a  rain,  the  moisture  soon  disappears  and  the  pools  of  water  dry  up.     The  air  has 
absorbed  the  moisture,  which  the  heat  of  the  sun  has  changed  to  an  invisible  vapor.     This 
process  is  called  evaporation. 

17.  Dew  Point. — The  amount  of  water  the  air  can  hold,  depends  on  the  temperature 
of  the  latter.    Warm  air  will  contain  a  great  deal  more  of  moisture  than  cold  air.    When  the 
air  contains  all  the  vapor  it  can  hold,  it  is  said  to  be  saturated,  or  at  the  dew  point. 


TEMPERATURE, 
FAHRENHEIT. 

WT  OP  VAPOR, 
IN  GRAINS. 

TEMPERATURE, 
FAHRENHEIT. 

W'T  OF  VAPOR, 
IN  GRAINS. 

TEMPERATURE, 
FAHRENHEIT. 

W'T  OF  VAPOB, 
IN  GRAINS. 

0° 

0.55 

65° 

6.79 

96° 

17.65 

10° 

0.84 

70° 

8.00 

98° 

18.69 

203 

1.30 

75° 

9.37 

100° 

19.79 

32° 

2.13 

80° 

10.95 

101° 

20.36 

40° 

2.86 

85° 

12.75 

102° 

20.94 

5(T 

4.09 

90° 

14.81 

103° 

21.53 

55° 

4.86 

92° 

15.71 

104° 

22.15 

60° 

5.75 

94° 

16.54 

105° 

22.77 

18.  When,  however,  the  temperature  falls  below  the  dew  point,  the  excess  of  moisture 
appears  either  as  rain,   snow,   hail,   dew,  fog,  or  clouds.    In  the  foregoing  table,  you 
will  find  the  weight  of  water  which  a  cubic  foot  of  air,  at  different  temperatures,  may 
contain. 

19.  Rain. — If  air  at  100°  F.  pass  over  the  ocean,  it  will  absorb  a  great  amount  of  mois- 
ture— nearly  20  grains  per  cubic  foot.    When  this  warm  air  strikes  the  cold  mountain  tops  of 
some  continent,  its  temperature  is  suddenly  lowered — perhaps  to  65°  F. 

20.  But  at  65°  F.,  the  air  can  hold  only  one-third  as  much  moisture  as  at  the  former  tem- 
perature.    Hence  the  vapor  is  condensed  or  again  changed  to  water,  which,  falling  as  rain, 
saturates  and  fertilizes  the  porous  soil  of  the  Earth. 

21.  The  average  annual  rainfall  of  the  United  States  is  about  39  inches  ;  that  of  Europe 
is  36  inches.     The  greatest  annual  rainfall  occurs  in  the  Himalaya  mountains.     Here,  in 
certain  regions,  the  rainfall  has  exceeded  660  inches  in  one  year.1 

22.  Snow. — Snow  is  formed  when  the  vapor  of  water  passes  directly  into  a  solid  state. 
It  may  therefore  be  called  frozen  moisture.    Snow  can  occur  only  when  the  temperature 
is  at  or  below  32°  F. 

23.  Examined  with  the  microscope,  snowfiakes  are  seen  to  be  crystals  of  wonderful 
symmetry  and  beauty.    Notice  that  each  crystal  is  six-sided  or  six-pointed,  and  that  the 
angles  are  similar. 


The  distribution  of  rain  will  be  considered  in  the  chapter  on  climate. 


THE     WATER     OF    THE    ATMOSPHERE. 


59 


24.  Hail.  —  Hail    is    frozen    rniii, 

and  is  usually  formed  at  a  great  height. 
Thunder  and  lightning  often  accompany 
hail  storms.  Ordinarily,  hail  stones  are 
about  the  size  of  rain  drops ;  but  in  many 
instances  they  are  much  larger,  some- 
times exceeding  two  inches  in  diameter. 

25.  Hail  storms  are  of  very  short 
duration — seldom  lasting  longer  than  ten 
or  fifteen  minutes,  but  they  are  always 
severe  while  they  last.     The  severest  hail 
storms  of  which  there  is  any  record,  have 
occurred  in  the  northwestern  part  of  the 
Mississippi  valley.1 

26.  Dew. — Dew  is  the  moisture  that 

collects  in  little  drops  on  the  leaves  and  snow  crystals. 

the  grass,  during  clear,  still  nights. 

27.  To  understand  why  and  how  dew  thus  forms,  we  must  again  consult  the  table  on 
page  58,  to  find  how  much  moisture  the  air  can  contain  at  a  given  temperature. 

28.  If  the  temperature  during  the  day  is  80°  F.,  the  air  may  hold  nearly  11  grains  of 
moisture  per  cubic  foot.     But  just  after  sunset,  the  surface  of  the  Earth  begins  to  cool 
rapidly — much  more  rapidly  than  the  air. 

29.  When  the  temperature  has  fallen  to  perhaps  60°,  the  air  near  the  ground,  also  cooled 
to  the  same  temperature,  can  therefore  no  longer  hold  more  than  half  as  much  moisture. 
The  surplus  is  deposited  as  dew. 

30.  In  the  morning,  as  soon  as  the  sun  has  warmed  the  Earth,  it,  in  turn,  warms  the 
air,  which  can  once  more  hold  the  moisture.    Hence  the  dew  soon  disappears  by  the  vaporiza- 
tion of  the  moisture  which  formed  it. 

31.  Very  frequently  there  are  nights  during  which  no  dew  forms.     If  the  sky  be  over- 
cast with  clouds,  no  dew  will  form,  because  the  clouds  do  not  permit  the  Earth  to  part  with 
the  heat  it  has  stored  up  during  the  day. 

32.  A  strong-  wind  will  prevent  the  formation  of  dew,  because  none  of  the  air  remains 
in  contact  with  the  Earth  long  enough  to  be  cooled  below  the  dew  point. 

33.  Most  frequently, there  is  none  deposited,  because  the  atmosphere  contains  no  more 
moisture  than  it  can  hold  at  the  lowest  temperature  which  occurs  during  the  night — that  is, 
the  temperature  does  not  sink  to  the  dew  point. 

34.  Dew  forms  most  copiously  in  the  vicinity  of  the  sea  coast,  and  in  places  well 
supplied  with  fresh  water.     There  are  some  localities  far  inland,  in  which  dew  seldom  or 
never  forms. 


35.  More  dew  forms  near  the  ground  than  at  a  short  distance  above  it. 
because  the  temperature  rises  steadily  as  the  distance  from  the  ground  increases. 


This  is 


1  When  a  large  hail  stone  is  cut  in  two,  it  is  found  to  be  composed  of  alternate  layers  of  snow  and  ice.  The  cause  of 
this  phenomenon  is  not  known.  It  has  been  attributed  to  the  whirling  action  of  the  wind,  whereby  the  hail  is  carried  suc- 
cessively into  warmer  and  colder  layers  of  air,  receiving  a  coating  of  water  in  the  former,  which  freezes,  and  of  snow  in 
the  latter.  This  explanation  is  theoretical,  and  not  at  all  satisfactory. 


60 


MONTEITJf'S    NEW    PHYSICAL     GEOGRAPHY. 


36.  Frost. — Frost  is  frozen  dew. 
Whenever  the  temperature  falls  be- 
low 32°  F.,  the    moisture    deposited 
consists  of  minute  icicles  instead  of 
small  drops  of  water.1 

37.  Fogs. — Fogs  are  masses  of 
vapor  partly  condensed,  resting  on 
the  surface  of  the  Earth.  It  is  thought 
by  some  authorities  that  the  minute 
globules  composing  the  fog  are  hol- 
low— that  is,  air  bubbles  of  exceed- 
ingly  small    size ;    by    others,  it    is 
claimed   that   they   are   very   small 
drops  of  water. 

38.  Fogs  prevail  when  the  air 
is    just    below  the    dew  point    and 
cannot  hold  quite  all  of  the  moisture 
present.     With  a  rising  temperature, 
the  fog  disappears  because  the  air 
can  then  hold  a  greater  amount  of 
moisture. 

39.  Fogs  seldom  reach  more  than 
four  or  five  hundred  feet  above  the 
ground — often,  not  half  that  height. 
An  observer  on  a  mountain  may  fre- 
quently see  the  valley  below  envel- 
oped in  a  dense  fog,  while  above  him 
the  sky  is  perfectly  clear. 

40.  Clouds. — Clouds  differ  from 
fogs  in  position  only,  the  latter  rest- 
ing on  the  ground,  while  the  former  are  usually  high  in  the  air.    Clouds  are  named  according 
to  their  form  and  appearance. 

41.  Cirrus 2  clouds  are  those  light,  feathery  clouds  which  sailors  call  cat-tails.     They 
are  always  very  high,  and  it  is  probable  that  they  consist  of  minute  ice  crystals. 

42.  Cumulus 3  clouds  are  so  called  because  they  seem  to  be  thrown  up  in  heaps  or 
piles.     The  cumuli  are  summer  clouds,  and  are  supported  by  the  warm,  ascending  currents  of 
air  from  the  Earth.     They  begin  to  form  after  sunrise,  are  heaviest  during  the  middle  of  the 
day,  and  disappear  after  sunset. 

43.  Stratus 4  clouds  are  the  horizontal  bands  of  cloud  matter  near  the  horizon,  often 


Various  kinds  of  clouds.     One  bird  in  the  illustration  is  in  the  Cirrus  ;  two  are  in 
the  Cumulus  ;  three,  in  the  Stratus ;  and  four,  in  the  Nimbus. 


1  Frosts  are  far  more  apt  to  occur  in  valleys  and  river-bottom  lands  than  on  hill  sides.  The  intelligent  fruit-grower 
recognizes  this  fact,  and  selects  a  hill  or  a  mountain  side  for  his  orchard,  rather  than  the  alluvial  bottom  lands.  Orchards 
situated  on  a  ridge  of  land,  or  on  the  foot  hills,  are  seldom  troubled  by  early  frosts,  while  those  on  the  bottom  lands  frequently 
fail  year  after  year. 

8  Cirrus. — From  the  Latin  cirrus,  a  feather.  3  Cumulus. — From  the  Latin  cumulus,  a  heap  or  pile. 

4  Stratus. — From  the  Latin  stratus,  a  layer. 


THE     WATER     OF    THE    ATMOSPHERE. 


seeming  to  be  arranged  in  layers.     They  usually  appear  at  sunset,  and  sometimes  continue 
through  the  night,  but  generally  disappear  at  daybreak. 

44.  The  nimbus 1  is  the  storm  cloud.     It  is  of  a  dark  hue,  and  shapeless.    It  hangs  low 
and  covers  the  whole  sky.     The  lower  part  of  the  nimbus  cloud  consists  of  raindrops  ;  the 
central  portion,  of  mist ;  and  the  upper,  of  fog,  or  cloud  mist.    Cumulus  and  stratus  clouds 
may  become  rain  clouds,  as  they  differ  from  the  nimbus  in  form  only. 

45.  Cirro-stratus,  cumulo-stratus,  and  cirro-cumulus  are  modifications  of  those  already 
described.     Cirrus  clouds,  especially  when  they  are  observed  at  sea,  are  often  the  fore- 
runners of  a  storm.     No  other  clouds  are  watched  with  such  interest  by  sailors  as  the  cirrus 
cloud. 

46.  Economy. — Were  it  not  for  the  moisture  of  the  atmosphere,  both  the  heat  of  day 
and  the  cold  of  night  would  be  intolerable.     But  the  small  amount  of  vapor — scarcely  one 
part  in  a  hundred — acts  as  a  screen  which  intercepts  the  fierce  heat  of  the  sun  during  the 
day,  and  gives  it  out  at  night. 

47.  In  intercepting  and  absorbing  the  heat  of  the  sun,  the  moisture  of  the  air  is  more 
than  seventy  times  as  powerful  as  the  air  itself. 

48.  In  regions  like  the  Libyan  desert,  where  the  air  is  unusually  dry,  the  day  tempera- 
ture sometimes  exceeds  140°  F.,  while  at  night,  water  in  shallow  vessels  may  be  frozen. 


WHAT  HAS  BEEN  TAUQHT  IN  CHAPTER  IX. 


Tfie  surface  of  the  land  oives  Us  present  ap- 
pearance chiefly  to  the  action  of  ivater. 

Water  is  composed  of  two  gaseous  elements, 
oxygen  and  hydrogen,  chemically  combined. 

Below  32°  F.,  water  is  a  solid  ;  and  above  212° 
F.,  a  vapor. 

Water  requires  more  heat  to  warm  it  than  any 
other  substance  occurring  free  in  nature,  and  it 
also  parts  with  its  heat  more  sloivly. 

All  fresh  water  in  the  Earth  came  from  the 
ocean. 

Tlie  air  has  the  property  of  taking  up  water 
in  the  form  of  vapor. 

The  warmer  the  air,  the  greater  the  amount 
of  moisture  it  will  absorb. 

Wlien  air  loaded  with  moisture  is  cooled,  it 
gives  off  the  excess  of  moisture  as  rain,  hail, 
snow,  dew,  fog,  or  clouds. 

Deiv  is  the  moisture  deposited  on  or  near  the 
ground  when  the  air  has  slowly  cooled  below  the 
point  of  saturation. 


Air  containing  all  the  moisture  it  can  hold  at 
a  given  temperature,  is  said  to  be  saturated. 

Unless  the  air  cools  below  the  point  of  satura- 
tion, no  dew  is  deposited. 

Snow  is  formed  when  the  vapor  of  water  passes 
at  once  into  a  solid  state. 

Frost  is  frozen  detv,  forming  only  when  the 
temperature  of  the  air  sinks  below  the  freezing 
point. 

Fogs  are  masses  of  vapor  in  a  state  of  partial 
condensation,  resting  on  or  just  above  the  Earth's 
surface. 

Clouds  are  classified  as  Cirrus,  or  feather 
clouds;  Cumulus,  or  pile  clouds;  Stratus,  or 
layer  clouds ;  and  Nimbus,  or  rain  clouds. 

The  small  amount  of  moisture  in  the  atmos- 
phere being  a  poor  conductor  of  heat,  shields  the 
Earth  from  much  of  the  sun's  heat  during  the 
day,  and  prevents  much  of  the  heat  received  dur- 
ing the  day  from  escaping  at  night. 


1  Nimbus. — From  the  Latin  nimbus,  a  storm  cloud. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


CHAPTER      X. 

THE     WATERS     OF     THE     COISTTIiSrENTS. 

SPRINGS    AND    LAKES. 

1.  The  water  which  is  raised  from  the  ocean  as  vapor,  and  is  carried  away  by  the 
winds  and  poured  upon  the  dry  land  as  rain,  evaporates,  sinks  into  the  ground,  or  else 
flows  off  upon  its  surface.     When  it  flows  off  upon  the  surface,  rivers,  creeks,  and  brooks 
are  formed  ;  when  it  sinks  into  the  ground,  springs  and  underground  reservoirs. 

2.  Origin   of  Springs. — A  portion  of  the  water  which  soaks  into  the  ground  sinks 

until  it  comes  to  a  layer  of  hard 
rock  or  clay  through  which  it  can- 
not pass,  while  another  portion  is 
retained  in  the  porous  rock  and 
soil,  just  as  it  might  be  held  by  a 
sponge.1 

3.  If  a  hole  be  sunk  into  water- 
soaked   ground,   it    is   immediately 
filled  with  water  forced  out  by  the 
pressure  of  water  above  and  around 
it.     In  this  manner,  our  wells  are 
kept  full. 

4.  If   there   are    cavities   in  the 
ground,  they  also  will  be  filled  with 
water.     When  such  cavities  are  on 
sloping  ground,  the  pressure  of  wa- 

Section  of  the  ground  or  rock,  showing  how  wells  are  supplied.-A,  The  ±        ahnvp  fnrPP<*  it  to   thf    mirfaPP   at 

part  through  which  the  rain  water  percolates  ;  C,  Rock  or  clay  impervious  to 

water ;  B,  Seam  or  stratum  in  which  the  water  passes  ;  D,  Level  of  water  in  a   lower   level, 

porous  ground. 

5.  The  stream  of  water  flowing 

from  this  channel  is  a  spring.     Sometimes,  there  is  a  cavity  or  underground  basin  in  which 
the  water  collects,  but  quite  as  of  ten,  the  whole  supply  is  held  in  the  porous  soil,  and  trickles 
out  through  some  channel  which  the  water  itself  has  made. 

6.  The  water  will  flow  so  long  as  the  level  of  the  reservoir  is  higher  than  the  spring. 
When  this  is  no  longer  the  case,  as  after  a  long  drought,  the  spring  ceases  to  flow. 

7.  Occasionally,  the  water  from  running  streams   finds  a  small  passage-way  unde* 
ground,  and  comes  again  to  the  surface  at  some  distance  from  its  starting  point.     Many 
of  the  springs  on  the  prairies  and  the  plains  may  be  thus  explained. 

8.  The  picture  on  the  next  page  explains  how  springs  are  formed.    The  porous  soil 
into  which  the  water  soaks  is  underlaid  by  hard  clay  or  by  rock,  through  which  it  cannot 
readily  pass. 


1  Light.porous  soils  and  sandstones  will  hold  nearly  half  their  bulk  of  water. 


THE  WATERS  OF  THE  CONTINENTS. 


63 


9.  Artesian  Wells. — When  an 
underground  reservoir  is  tapped   by 
drilling  or  boring  through  the  over- 
lying rock,  the  pressure  is  often  so 
great  as  to  force  the  water  above  the 
surface.    These  artificial  channels  are 
called  artesian  wells.1 

10.  Artesian    wells    have    been 
sunk  to  great  depths  — 2,300  feet  or 
more — in  order  to  reach  underground 
streams  of   water.       Sometimes    the 
water  spouts  above  the  surface,  but 
oftener  it  does  not  quite  reach  to  the 
top  of  the  ground. 

11.  Hot  Springs.— In  ordinary 
cases,  the  temperature  of  spring  water 
varies  from  50°  to  60°  F. ;  but  in  many 
places,  there  are  springs  whose  waters 
are  hot  and  even  boiling. 


Artesian  Wells.— A,  A,  A,  Strata  impervious  to  water ;— B,  B>  Seams  or  strata 
of  porous  rock  saturated  with  water ; — D,  D,  Borings  in  the  ground  or  rock, 
called  artesian  wells. 


Section  of  a  Hill,  whence  issues  a  Spring.— A,  Loose  earth  or  broken  rock 
through  which  the  water  sinks ;  C,  Solid  rock  or  hard  clay  not  penetrated  by 
water ;  B,  Seam  or  channel  in  which  the  water  flows. 


12.  Their  heat  is  derived  either 
from  the  chemical  decay  of   rocks, 
or  else  from  the  heated  volcanic  mat- 
ter surrounding  the  reservoir.     Most 
of  the  known  hot  springs  are  in  vol- 
canic regions. 

13.  Mineral  Springs. — The  wa- 
ters of    many  springs,  in   trickling 
through   porous    rock,  dissolve   and 
retain    the   more    soluble   minerals, 
such    as    salt,    carbonate    of    soda, 
lime,   and  various    combinations  of 
sulphur.     They  are  commonly  called 
"mineral"  springs.2 

14.  Mineral  spring  waters  usually 
are  hot,  but  some  of  the  most  cel- 
ebrated in  the  world,   as    those   of 
Saratoga,   New  York,   and    Seltzer, 
Germany,  are  cold  springs. 


1  In  that  part  of  southern  California  lying  between  the  coast  mountains  and  thePacific  ocean,  thereare  several  thousand 
artesian  wells,  ranging  from  100  feet  to  1,200  feet  in  depth.  The  first  of  these  were  spouting  wells,  hut  the  number  is  now 
so  great,  that  hut  few  of  them  force  the  water  above  the  surface.  By  their  means,  millions  of  acres  of  land  are  now  fruitful 
which  would  be  unproductive  without  them.  A  number  of  artesian  wells  have  been  successfully  driven  in  the  Great  Desert 
by  the  orders  of  the  French  Government  Survey. 

3  Mineral  springs  may  be  calcareous,  containing  carbonate  of  lime ;  soda  springs,  containing  soda ;  silicious  springs,  or 
geysers,  containing  silica  or  sand  in  solution  ;  sulphur  springs,  containing  hydrogen  sulphide  or  other  sulphur  compounds  ; 
chalybeate  springs,  containing  iron  ;  acid  soda  springs,  containing  large  quantities  of  carbon  dioxide.  The  latter  are  always 
cold  springs.  "Seltzer,"  "Vichy,"  and  "Congress"  waters  are  taken  from  such  springs. 


64  MONTEITH'S    NEW   PHYSICAL     GEOGRAPHY. 

15.  If  carbonate  of  lime  be  present  in  the  water  of  a  spring,  much  of  it  is  deposited. 
If  the  water  fall  drop  by  drop,  icicle-shaped  deposits  called  stalactites  are  formed  at  the 
ceiling,  while  similar  deposits  called  stalagmites  are  built  up  from  the  floor  of  the  cavity.1 

16.  Mineral  Oil  Springs. — In  California,  Pennsylvania,  Syria,  and  Turkestan,  tar 
and  petroleum  springs  abound.     In  the  island  of  Trinidad,  near  the  mouth  of  the  Orinoco, 
the  accumulations  of  bitumen2  or  mineral  "pitch"  have  formed  a  large  lake. 

17.  Periodical  Springs. — Periodical  or  intermittent  springs  are  those  whose  waters 
flow  at  irregular  intervals.     It  is  thought  that  their  irregular  flow  is  due  to  the  siphon- 
shape  of  the  channel  through  which  the  water  is  discharged. 

18.  Water   Supply  of  Islands. — Supplies  of  fresh  water  are  usually  found  even  on 
small  islands — especially  coral  islands.     Wells  may  be  sunk  from  which  fresh  water  is 
obtained,  even  though  the  surface  of  the  water  in  the  well  be  no  higher  than  the  level  of 
the  surrounding  ocean. 

19.  The  explanation  of  this  apparently  strange  fact  is  simple.    After  a  heavy  rain,  the 
water  sinks  into  the  sand,  and  being  lighter  than  the  sea- water,  rests  upon  it,  as  is  shown 
in  the  accompanying  cut. 

B 

^^^^^W^^i^^    • "  "  '  •^•y^- 

A,  B,  Sea  level ;— C,  D,  Fresh  water  from  rain  resting  on  salt  water,  with  which  it  does  not  mix  because  it  is  lighter. 

20.  Formation  of  Lakes. — Much  of  the  water  that  does  not  evaporate  or  sink  into 
the  soil  collects  in  natural  depressions  of  land. 

21.  If  it  collect  in  this  basin  or  depression  more  rapidly  than  it  evaporates,  a  lake  is 
formed.    The  water  either  continues  to  collect  until  it  rises  to  the  rim  of  the  basin  and 
overflows,  or  else  it  spreads  over  the  land  until  it  covers  a  surface  so  great  that  precisely 
as  much  evaporates  as  flows  into  the  basin. 

22.  Classification. — Thus  we  see  there  are  two  classes  of  lakes — those  having  out- 
lets and  those  having  none.    The  waters  of  the  former  are  fresh  ;  those  of  the  latter  are 
usually  salt.     The  latter  are  met  with  in  great  continental  plains,  where  there  is  but  little 
chance  for  their  waters  to  run  off.     For  this  reason,  the  lakes  occurring  in  such  regions  are 
commonly  called  " steppe"  lakes. 

23.  Each  continent  has  its  lake-systems.      The  largest  is  in  North  America,  which 
alone  contains  a  greater  number  of  lakes  than  all  the  other  continents  together. 

24.  Lakes  of  North  America. — The  Great  Lakes  of  North  America  have  an  area  of 
more  than  100,000  square  miles — scarcely  less  than  the  combined  area  of  all  the  remaining 
bodies  of  fresh  water  in  the  world.     The  basins  drained  by  them,  however,  are  but  little 
larger  than  the  lakes  themselves,  as  each  basin  is  filled  nearly  to  the  brim. 

1  The  material  thus  deposited  is  usually  known  as  travertine.  Twigs,  medallions,  coins,  etc.,  placed  where  they  can  be 
sprayed  with  the  waters  of  these  springs,  are  quickly  covered  with  a  deposit  of  carbonate  of  lime.  The  so-called  petrified 
moss  consists  usually  of  the  fine  rootlets  of  plants  covered  with  accretions  of  limestone. 

8  This  substance,  variously  called  "pitch,"  "asphalt,"  and  "  brea,"  is  much  used  in  street-paving,  for  making  a 
tough,  artificial  building-stone,  and  also  as  a  covering  for  foundation- walls. 


THE     WATERS     OF    THE     CONTINENTS. 


65 


Lake  Superior.  Lake  Huron.         Lake  Erie.  Niagara      Lake  Ontario.      1000  islands.  Montreal.  Quebec. 

St.  Mary's  River.  River  and  Palls. 

A  Sectional  View  of  the  Great  Lakes  and  the  St.  Lawrence  River,  looking  North. 

25.  The  water  of  these  lakes  is  supplied  chiefly  by  rain,  but  partly  by  a  few  small 
rivers.  The  average  rainfall  in  the  region  of  the  lakes  is  36  inches  a  year — an  amount 
sufficient  to  keep  them  full  and  to  supply  the  St.  Lawrence  river,  their  outlet. 

26".  The  situation  of  these  lakes,  in  terraces,  one  higher  than  another,  is  an  interesting 
feature.  The  rivers  draining  the  waters  of  these  lakes  contain  falls  and  rapids. 

27.  Lakes  Superior  and  Huron,  the  deepest  of  this  group,  have  a  depth  of  1,008  and 
702  feet,  respectively.     The  bottom  of  the  former  is  409  feet  below  sea  level. 

28.  Lake  Erie  has  an  average  depth  of  less  than  70  feet.     A  severe  storm  stirs  its  waters 
to  the  bottom.     For  this  reason,  and  also  because  there  is  so  little  sea  room,  Lake  Erie 
during  a  storm  is  a  very  dangerous  body  of  water  for  sailing-vessels. 

29.  A  chain  of  smaller  lakes  lies  northwest  of  the  Great  Lakes.     Indeed,  so  closely 
connected  are  the  lakes,  that  water  communication  between  Lake  Superior  and  Hudson 
Bay  is  sometimes  possible  for  canoes. 

30.  Aji  arc  of  a  great  circle  drawn  from  a  point  a  few  miles  west  of  Buffalo  to  the 
western  side  of  Geography  island,  near  the  mouth  of  the  Mackenzie  river,  will  pass  through 
nearly  all  of  the  more  important  fresh  water  lakes  on  the  continent. 

31.  African  Lakes. — The  principal  lake  system  of  Africa  is  in  the  eastern  part  of  the 
continent,  at  an  elevation  varying  from  3,000  to  5,000  feet  above  the  sea  level.     Like  the 
Great  Lakes,  their  basins  are  filled  to  the  brim. 

32.  The  lakes  of  Africa  are  in  comparatively  unexplored  regions.      Most  of  them 
are  drained  by  the  Congo  or  Livingstone,  and  Nile  rivers.     The  principal  are  Victoria,  the 
largest  in  the  world,  Albert,  and  Tanganyika  (tahn-gahn-yee'kah). 

33.  Lake  Tchad  (chad),  a  fresh  water  lake  in  Soudan,  has  an  area  varying  from 
15,000  to  50,000  square  miles,  the  latter  being  its  area  during  the  wet  season.      At  high 
water  it  overflows,  the  Bahr-el-Gazel  being  its  outlet. 


66  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


34.  Lakes  of  South  America.— There  are  but  two  lakes  of  considerable  size  in  South 
America,  Maracaybo  (mah-rah-klbo)  and  Titicaca  (tit-e-kah'kah).     The  latter  has  an  altitude 
of  12,000  feet. 

35.  Lakes  of  Europe. — The  lakes  of  Europe  form  two  groups.     Those  in  the  Alpine 
region  are  renowned  for  their  beautiful  scenery.     The  second  group  is  situated  in  Russia, 
Lake  Lad'oga  being  the  largest.     Most  of  the  latter  group  are  steppe  lakes. 

36.  The  water  of  lake  Elton,  in   Russia,  contains  about  twenty-nine   per  cent,  of 
salt.     In  summer,  many  of  the  smaller  steppe  lakes  of  Russia  dry  up,  leaving  beds  of 
salt  and  other  mineral  matter. 

37.  Lakes  of  Asia. — Lake  Baikal  (bi'kahl),m  Siberia,  is  the  largest  fresh  water  lake  in 
Asia.     Its  waters  are  frozen  six  months  in  the  year.     Lake  Sirikol,  the  source  of  the  Oxus 
river,  has  an  altitude  of  15,600  feet  above  the  sea  level. 

38.  Lakes  of  Australia. — Most  of  the  Australian  lakes  are  steppe  lakes.     They  are 
situated  in  the  southern  and  southwestern  part  of  the  continent.     Lakes  Eyre,  Gairdiner, 
and  Amadeus,  are  the  most  important. 

39.  Salt  Lakes. — Of  the  various  salt  lakes,  the  Caspian,  Dead,  and  Aral  seas,  and 
Great  Salt  Lake,  are  the  most  noted.     The  first  two  are  below  the  sea  level. 

40.  The  Caspian  and  Aral  seas  are  thought  to  have  been,  in  recent  times,  arms  of 
the  ocean;    but  the   fact  that  their  waters  are  much  fresher  than   those  of  the  ocean, 
makes  this  theory  somewhat  doubtful. 

41.  The  Caspian  sea  receives  the  waters  of  the  Ural,  Volga,  and  several  other  large 
rivers.     The  water  supplied  by  these  rivers  is  equal  to  the  amount  lost  by  evaporation. 

42.  The  basin  of  the  Caspian  sea  is  a  very  large  one  and  seems  to  be  of  recent  forma- 
tion.    Petroleum,  tar,  and  naphtha  springs  are  numerous  throughout  the  neighborhood  of 
the  sea.     Its  surface  is  eighty-four  feet  below  the  ocean  level. 

43.  During  certain  periods,  large  quantities  of  naphtha  and  petroleum  accumulate  on 
the  surface  of  the  Caspian  sea.     In  1869,  an  extensive  and  destructive  conflagration  occurred 
by  the  accidental  ignition  of  these  substances. 

44.  The  Dead  Sea,  whose  surface  is   1312  feet  below  the  ocean  level,  is  the  most 
remarkable  depression  in  the  world.      It  is  situated  about   eighteen  miles   east  of  Jeru- 
salem, and  extends  over  an  area  of  400  square  miles. 

45.  The  region  in  which  it  is  situated  is  volcanic  and  is  still  subject  to  earthquakes. 
There  is  strong  evidence  that  this  depression  was  formed  about  1900  B.  c.,  during  an  earth- 
quake accompanied  by  volcanic  action.1 

46.  The  river  Jordan  is  its  only  inlet  of  any  importance,  and  it  has  no  outlet.     The 
basin  is  a  long  one,  but  very  narrow — hardly  twenty -five  miles  in  width. 

47.  The  water  level,  during  the  rainy  season,  is  about  ten  feet  higher  than  in  the  dry 
season  of  the  year.     This  enormous  surplus  is  evaporated  during  the  hot  summer  months, 
at  which  time  the  average  temperature  in  the  vicinity  of  the  lake  is  about  93°  F. 

1  The  site  of  the  Dead  Sea  is  the  Vale  of  Siddim,  which  Lot  chose  for  his  habitation  when  he  parted  from 
Abraham.  Its  climate  was  then  vastly  different  from  that  of  the  present  time.  There  were  formerly  two  cities  of 
considerable  importance — Sodom  and  Gomorrah.  These  were  destroyed  in  the  convulsion  of  nature,  described  in  Gen. 
zix,  28.  The  ruins  of  the  ancient  city,  Zoar,  have  recently  been  discovered  near  the  western  shore. 


THE  WATERS  OF  THE  CONTINENTS. 


67 


48.  There  is  some  evidence  that  the  rainfall  in   Syria  has  been  steadily  decreasing 
during  the  last  2,000  years.     Should  this  continue,  the  drying  up  of  the  Dead  Sea  is  a 
question  of  time  only. 

49.  Sulphur,  gypsum,  pitch,  and  petroleum  are  found  near  the  borders  of  the  Dead 
Sea.      There  is  but  one  other  body  of  water  in  the  world  (Lake  Elton)  which  contains  so 
much  of  mineral  salts  in  solution ;  every  100  Ibs.  of  water  contain  26  of  salt. 

50.  Great  Salt  Lake. — Great  Salt  Lake  of  Utah  is  another  remarkable  example  of 
the  steppe  lakes.     That  the  area  of  this  lake  was  formerly  much  greater,  may  be  seen  by 
the  old  shore  lines,  900  feet  higher  than  the  present  water-level.     For  the  last  twenty-five 
years,  however,  there  has  been  a  steady  increase  in  its  depth. 

51.  There  are  several  streams  of  water  flowing  into  Great  Salt  Lake ;  the  Jordan  (of 
Utah)  is  the  largest.    The  soil, for  many  miles  about  this  lake,  is  impregnated  with  lime,  soda, 
and  potash,  all  of  which  are  carried  into  the  lake  by  tributary  streams. 

52.  Origin  of  Salt  Lakes. — We  can  now  understand  why  the  waters  of  those  lakes 
which  have  no  outlets  are  salt.     Soils  and  rock  contain  small  quantities  of  salt  and  other 
minerals  which  are  dissolved  by  the  water  as  it  flows  through  them. 

53.  If  the  water  flows  into  a  lake  having  no  outlet,   it  evaporates  and  leaves  the 
salt ;  but  if  there  is  an  outlet,  both  water  and  salt  are  carried  to  the  ocean.1 


WHAT  HAS  BEEN  TAUGHT  IN  CHAPTER  X. 


Springs  are  formed  by  tJie  ivater  which, 
felling  as  rain,  sinks  into  the  Earth. 

The  water  sinks  until  it  meets  a  layer  of 
clay  or  of  rock,  through  ivhich  it  cannot  pass. 

It  collects  in  underground  reservoirs  and 
channels,  or  saturates  the  porous  soil. 

Wlien  it  emerges  to  the,  surface,  the  escaping 
water  »is  called  a  spring. 

Underground  streams  of  water  are  often 
tapped  by  boring  through  the  overlying  strata. 
The  artificial  springs  thus  formed  are  called 
artesian  ivells. 

Spring  waters  have  usually  a  temperature 
varying  from  4O°  to  6O°  F. 

In  volcanic  regions,  the  temperature  of  their 
waters,  owing  to  their  contact  with  heated 
rocks,  is  often  hot — sometimes  even  reaching 
the  boiling  point. 

When  the  subterranean  waters  take  up  the 
soluble  substances  of  the  rocks  through  tvhich 
they  pass,  mineral  springs  are  formed. 


Lake-basins  are  natural  depressions  in  the 
Earth's  surface  in  which  rain-water  collects. 

If  the  water  collect  more  rapidly  than  it 
evaporates,  a  lake  is  formed. 

Lakes  are  of  two  classes — those  which  have 
outlets  and  those  which  have  none. 

The  waters  of  the  former  are  fresJi ;  those  of 
the  latter,  usually  salt.  TJie  salt  is  dissolved 
from  the  soil  through  which  the  water  flows. 

The  Great  Lakes  of  North  America  constitute 
the  largest  body  of  fresh  water  in  the  ivorld. 

The  lake  system  of  Africa  ranks  next  in  size 
to  that  of  North  America. 

TJie  lakes  of  Asia  and  western  Europe  are 
chiefly  steppe  or  salt  lakes. 

Tlie  Dead  and  Caspian  seas  are  below  the 
ocean-level. 

The  Caspian  sea  is  the  largest  salt  lake  in 
the  eastern  hemisphere. 

Great  Salt  Lake  of  Utah  is  the  largest  salt 
lake  of  the  western  hemisphere. 


1  Well  and  spring  waters   also  contain  salt,  although  the  amount  is  so  small  that  it  cannot  be  detected  by  the  taste. 


68 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


CHA.PTER     XI. 

RISERS     A.JSTD      D  R  ^  I  N  .A.  O 


1.  The  "water  falling  on  the  land  in  the  form  of 
rain  and  snow  is  sufficient  to  cover  the  continents  to 
a  depth  of  three  and  one-half  feet  each  year. 

2.  Of  this  amount,  perhaps  two-thirds  evaporates, 
and  the  remaining  third  flows  back  to  the  source  from 
which  it  came  —  the  ocean.1 

3.  The  Beginning  of  a  River.  —  The  sources  of 
most  rivers  are  in  mountains,  for  here  is  the  heaviest 
fall  of  rain  and  snow;   here,  also,  springs  are  most 
abundant. 

4.  The  water  that  trickles  from  a  spring  or  is  let 
loose  from  some  snow  drift  high  on  the  mountains, 
forms  a  little  r,ill  which  rushes  down  the  steep  slope 
toward  the  plain  below. 

5.  On  its  way,  it  is  joined  by  other  rills  in  their 
journey  to  the  ocean.     The  rivulet  thus  formed  tum- 
bles down  the  mountain  slopes  and  over  the  pebbled 
bottoms  of  the  gullies  which  it  has  worn. 

6.  Other  streams  swell  it  to  a  mountain  tor- 
rent.    Plunging  over  cliffs  in  cascades,  or  rushing 
down  steep  inclines  in  rapids,  it  cuts  a  channel  into 
the    hardest    rock,   and    either  tosses    aside  or  else 
ploughs  through  obstacles  happening  in  its  way. 

7.  After  a  long  and  tumultuous  passage,  it  reaches 
the  plain  at  the  base  of  the  mountains,  where  it  receives  the  waters  of  other  streams  that 
have  had  a  similar  journey. 

8.  Henceforth  the  conduct  of  the  river  is  wholly  changed.     No  longer  able  to  carry  the 
load  of  silt  and  gravel  which  it  has  scoured  from  the  bottom  and  sides  of  mountain  gorges, 
it  drops  all  but  the  lighter  portion  and  flows  around  obstacles  which  it  cannot  move. 

9.  So  long  as  the  current  is  swift  it  will  carry  this  sediment,  but  check  it  ever  so  little, 
and  some  of  it  sinks  to  the  bottom  to  form  a  bar  or  "shallow." 

10.  The  Middle  Course.  —  When  the  stream  has  reached  the  lowlands,  it  is  still  heavily 
laden  with  silt.     At  St.  Louis,  the  river  —  if  we  take  the  Missouri  and  Mississippi  as  an 
example  —  is  still  1,300  miles  from  the  Gulf,  and  375  feet  above  the  sea  level.     From  St.  Louis, 

1  The  foregoing  statement  must  be  considered  as  an  average  only.  In  certain  regions,  such  as  the  Great  Desert  and  Cen- 
tral Asia,  nearly  or  quite  all  of  the  water  disappears  by  evaporation  ;  while  in  northern  Asia  and  North  America,  the  water 
which  evaporates  is  less  than  one  fifth  of  that  which  falls. 


A  Mountain  Stream.— The  Upper  Course. 


RIVERS    AND    DRAINAGE. 


69 


A  River.-iThe  middle  course. 


the  river  flows  with  slightly  decreasing 
velocity,  on  ground  which  it  has  itself  spread 
over  the  valley.  There  are  no  banks  that  it 
has  not  built  for  itself,  and  having  built 
them,  it  can  just  as  easily  cut  them  away. 

11.  The  Lower  Course. — In  time,  the 
waters  reach  the  Gulf  of  Mexico,  after  a  con- 
tinuous passage  of   4,100  miles.      Here,  the 
current  is  checked  by  the  ocean  tides,  and 
the  restless  waters  throw  down  the  last  rem- 
nant of  their  burden  of  silt. 

12.  Thus  we  see  that  a  river  course  may 
consist    of    three  parts :    the  upper  course, 
where  its  work  is  erosive,  or  wearing ;  the 
middle  course,  in  which  it  is  chiefly  trans- 
porting, or  sediment-bearing ;  and  the  lower 
course,  where  it  builds  up  land  with  the 
sediment  brought  from  the  upper  course. 

13.  Effect  of  Velocity. — A  river  whose  current  flows  with  a  velocity  of  four  miles 
an  hour  will  carry  sixty-four  times  as  much  sediment  as  one  flowing  at  the  rate  of  two 
miles  an  hour ;  consequently,  a  slight  change  in  velocity  makes  a  very  great  difference  in 
its  carrying  capacity.1 

14.  Filling1  the  Channel. — Sediment  is  dropped  in  the  lower  course,  because  the  cur- 
rent is  checked ;  and  because  the  sediment  is  dropped,  it  is  plain  that  the  channel  must 
constantly  fill  up. 

15.  In  time, the  river  has  built  its  bed  and  its  banks  until  they  are  higher  than  the  sur- 
rounding land.     Until  a  season  of  high  water,  however,  it  still  flows  in  its  channel. 

16.  Then  it  overflows,  cutting  away  the  banks  that  it  had  itself  placed  there.     Through 
this  break,  or  crevasse,  the  waters  are  poured  over  the  surrounding  lowlands. 

17.  The  IVew  Channel.— After  the  high 
waters    have   subsided,   the    river  no    longer 
flows  wholly  in  its  old  channel.     In  various 
places,  it  has  made  a  new  one  ;  and  wherever 
the  channel  has  changed,  the  river  at  that 
point  has  selected  its  bed  in  lower  ground. 

18.  In  this  new  channel  the  filling  pro- 
cess immediately  begins,    and    continues  till 
another  freshet    turns   its  waters  elsewhere. 
Thus  has  the  work  progressed  for  centuries. 

19.  Shifting-  of  the   Channel. — During 
past  ages,  the  waters  of  the  Mississippi  river 

1  "It  has  been  calculated  that  a  velocity  of  three  inches  per  second  will  tear  up  fine  clay  ;  that  six  inches  will  lift  fine 
sand  ;  eight  inches,  sand  as  coarse  as  linseed  :  and  twelve  inches,  fine  gravel ;  a  velocity  of  twenty-four  inches  per  second  is 
required  to  sweep  angular  stones  of  the  size  of  a  hen's  egg." 


A  CREVASSE. ON  THE   MISSISSIPPI  RIVER 


A  River.— Making  a  new  channel. 


70 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


The  Lower  Course  of  a  River.— Dropping  its  burden  and  forming  a  delta. 


must  have  flowed 
in  all  parts  of  the 
valley  —  working 
in  the  same  man- 
ner that  it  works 
now — building  its 
banks  higher  than 
the  surrounding 
land,  and  then 
breaking  through 
them. 

20.  So  long  as 
the  Mississippi 
flows,  it  will  still 
bear  its  burden  of 
silt  to  the  Gulf  of 
Mexico,  and  the 
latter  will  de- 
crease in  size  un- 
til it  is  dry  land. 

21.  The  territory  north  of  the  gulf  was  formerly  an  arm  of  the  sea  as  far  north  as  St. 
Louis — or  farther.     All  of  that  land  has  been  formed  from  the  silt  brought  down  and  depos- 
ited by  the  waters  of  the  river. 

22.  The  lower  course  of  most  rivers — especially  those  flowing  through  level  plains — 
is  usually  very  crooked  and  winding.     The  distance  from  St.  Louis  to  the  mouth  of  the 
Mississippi  in  a  straight  line  is  700  miles  ;  by  the  river  channel  it  is  1,300  miles. 

23.  Were  the  river  to  flow  in  a  straight  line,  its  fall  would  be  7  inches  per  mile  ;  but, 
flowing  in  its  present  course,  the  fall  is  less  than  4  inches  per  mile. 

24.  Why  it  does  not  straighten  its  channel  and  thus  increase  its  velocity  seems  strange, 
until  we  consider  that  the  current  is  so  slow  that  the  water  cannot  carry  even  the  burden 
it  already  holds.    Hence,  it  drops  the  load  and  must  ever  afterward  flow  around  it. 

25.  Building  the  Valley. — Thus  we  see  that  while  in  the  upper  course  a  river  tends 
to  straighten  its  channel,  in  the  lower  course  it  constantly  lengthens  it. 

26.  The  sediment  carried  from  the  uplands  by  rivers  is  enormous.    In  places,the  deposits 
are  more  than  1,000  feet  deep.     Much  of  the  Great  Central  Plain  has  been  built  by  the  Mis- 
sissippi and  its  tributaries.1 

27.  Bars. — If  the  mouth  of  a  river  face  the  tide  wave,  a  bar  is  nearly  always  formed, 
because  the  silt  brought  down  by  the  river  is  forced  back  by  the  tide,  and  cannot  be  carried 
far  off  shore  by  the  river. 


1  '  It  must  have  been  but  yesterday  that  the  mound-builders  wrought  in  the  valley,  for  in  the  few  centuries  that  have 
elapsed  since  then,  the  surface  of  the  ground  has  risen  only  a  few  feet — not  enough  to  bury  their  works  out  of  sight.  How 
long  ago,  then,  must  it  have  been  that  the  race  lived  there,  whose  pavements  and  cisterns  of  Roman  trick  now  lie  seventy 
feet  under  ground  ?  And  if  we  cannot  answer  this  question,  how  shall  we  figure  up  the  sum  of  years  it  has  taken  to  fill  up 
the  valley  a  thousand  feet  deep  with  silt." — D.  A.  Curtis. 


RIVERS    AND     DRAINAGE. 


71 


28.  Bars  thus  formed  are  especially  dangerous  on  the  western 
coasts  of  continents.     Those  at  the  mouth  of  the  Columbia  river 
and  the  entrance  of  San  Francisco  bay  are  much  feared  by  pilots. 

29.  If,  however,  the  tide  wave  sweeps  at  right  angles  to  the 
current  of  the  river  at  its  mouth,  much  of  the  silt  will  be  borne 
away,  while,  if  the  tide  be  not  strong,  that  which  remains  may 
form  a  delta. 

30.  The  Delta. — The  figure  on  page  70  shows  the  manner  in 
which  a  river  extends  its  channel  into  the  sea.     The  network  of 
mouths  and  islands  is  called  a  "delta."1    There  the  river  drops 
the  last  of  its  silt. 

31.  The  stream  must  now  force  its  way  through  the  mud  flats 
which  are  constantly  growing  in  size,  and  its  waters  must  twice  a 
day  be  pushed  back  by  the  tide.     For  this  reason,  little  or  none  of 
the  sediment  can  be  carried  beyond  the  delta.2 

32.  About   7,500,000,000  cubic  feet  of  sediment  are  brought 

down  yearly  by  the  Mississippi 
river — enough  to  cover  a  square 
mile  of  land  to  the  depth  of  more 
than  270  feet. 


Chasm  of  Tugaloo  Kiver,  Georgia. 


Tocoa  Falls,  Georgia. 


33.  Thus,  for  more  than  fifty 

miles  the  Mississippi  has  pushed  its  way  into  the  sea,  bor- 
dered on  each  side  by  narrow  strips  of  land.  These  border 
strips  are  natural  levees  made  by  the  river  itself. 

34.  The  Po,  in  northern  Italy,  is  remarkable  for  the 
rapidity  with  which  it  has  built  its  delta.     Since  the  time  of 
Augustus  Csesar,  this  delta  has  been  pushed  seaward  20 
miles.   During  the  reign  of  that  emperor,  the  town  of  Adria, 
now  20  miles  inland,  was  a  seaport.3 

35.  Rapids  and   Cataracts. — It  sometimes  happens 
that  the  water  of  a  river  descends  abruptly  from  a  higher  to- 
a  lower  level.     This  is  accomplished  either  by  falls  or  by 
rapids. 

36.  If,  in  the  higher  level,  there  is  a  surface-layer  of 
hard  rock,  a  fall  or  cascade  is  the  result.     But  if  the  upper 
surface  is  soft  and  easily  worn  away,  rapids  are  formed 
instead. 


1  Delta. — The  name  of  the  Greek  letter  D,  made  thus,  A. 

2  The  delta  of  the  Mississippi  river  has  an  area  of  14,000  square  miles  ;  the  deltas  of  the  Nile  and  the  Ganges  cover  an 
extent  of  20,000  square  miles  each. 

8  In  order  to  guard  against  overflows,  the  lower  course  of  the  Po  has  been  flanked  by  levees  until  the  present  bed  of 
the  river  is  much  higher  than  the  land  on  either  side,  owing  to  the  constant  deposition  of  sediment.  Certainly  a  time  must 
come  when  the  levees  will  break  and  the  channel  of  the  river  change.  The  same  policy  of  levee  building  has  been  adopted 
in  the  case  of  the  lower  Sacramento  river,  where  to  the  natural  accumulation  of  sediment  have  been  added  the  "  tailings" 
from  the  hydraulic  mines.  With  the  lower  Mississippi,  a  different  plan  has  been  followed.  Here,  the  levees  and  jetties  have 
been  constructed  in  such  a  manner  as  to  increase  the  velocity  of  the  current,  thereby  forcing  the  water  to  scour  out  the  channel 
instead  of  filling  it.  This  carries  silt  out  beyond  the  delta. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Lachine  Eapids,  St.  Lawrence  River. 


37.  The  cataract  between  lakes  Erie 
and  Ontario,   where  the   Niagara  river 
falls  to  a  lower  terrace,  is  one  of  the 
most  celebrated  in  the  world.     The  Yo- 
semite  falls,  in  California,  are  an  extra- 
ordinary example  of  mountain  cascades ; 
one  of  them  having  an  uninterrupted 
fall  of  1,500  feet.     The  total  descent  of 
the  water  is  about  2,600  feet. 

38.  The  falls  of  the  Zambeze,  about 
360  feet  in  height,  rank  next  to  those  of 
the  Niagara  river.     The  Cascade  moun- 
tains are  celebrated  for  the  number  and 
beauty  of  their  waterfalls.   The  Cascades 
of   the    Santiam,   Willamette,   and   Co- 
lumbia rivers,  of  Oregon,  are  unsurpassed 

for  their  beauty  and  grandeur  by  any  others  in  the  world. 

39.  Erosive  Action. — The  wearing  or  erosive  power  of  rivers  is  almost  beyond  belief. 
The  canon  of  the  Colorado  has  been  cut  almost  vertically  to  a  depth,  in  many  places,  of  more 
than  a  mile. 

40.  Deep  gorges,  sometimes  exceeding  3,000  feet,  have  likewise  been  cut  by  the  Columbia 
river  and  its  tributaries.     The  canon  of  Crooked  river  is  especially  notable. 

41.  River  Basins. — A  river  system  comprises  a  river  and  all  its  branches.     The  surface 
of  land  drained  by  a  river  system  is  its  basin  or  territory. 

42.  The  rim  of  a  river  basin  is  called  a  watershed  or  divide.    Generally,the  divide  is 
a  mountain  range,  but  sometimes  it  is  an  imperceptible  ridge  in  some  plain. 

43.  Divides. — The  Height  of  Land  which  is  the  divide  between  the  Great  Lakes  and 
the  Mississippi  river  is  a  plain.     The 

taken  from  Chicago 


water  taken  from  Chicago  river  to 
feed  a  canal  discharging  into  a  trib- 
utary of  the  Illinois,  is  lifted  by  ma- 
chinery but  five  feet. 

44.  The  most  notable  divide  of 
North  America  is  in  the  Rocky  moun- 
tains.    Separated   by  a  few  miles  are 
the  sources  of  the  Missouri,  the  Co- 
lumbia, the  Athabasca,  and  the  Sas- 
katchewan. 

45.  Drainage.  —  North  America 
contains  several  large  drainage  basins, 
of  which  the  Mississippi  is  the  most 
important  and   the  largest.     East  of 
the  Appalachian  system  the  slope  is 
drained  by  numerous,  short  rivers  flow- 
ing into  the  Atlantic  ocean. 


The  Great  Continental  Divide. 


RIVERS    AND    DRAINAGE. 


73 


46.  The  rim  of  the  Mississippi  basin  is  formed  by  the  Rocky  mountains,  the  Height 
of  Land,  and  the  Appalachian  mountains.     This  basin  covers  an  area  of  one  and  a  quarter 
million  square  miles. 

47.  The  Pacific  slope  is  drained  by  the  Yukon,   Columbia,  Sacramento,  and  San 
Joaquin  (wah-keen'}  systems.     The  Yukon  river  is  second  to  the  Mississippi  only,  in  volume. 
Its  course,  though,  is  in  an  unexplored  region. 

48.  A  few  river  basins,  such  as  the  Humboldt,  the  Mojave  (mo-hah'-ve),  and  the  Amar- 
gosa — all  in  the  Great  Basin — have  no  outlet  to  the  sea. 

49.  Of  South  America,  the  great  drainage  basins  are  the  Amazon,  the  Orinoco, 
and  the  La  Plata.     During  the  rainy  season,  the  channels  of  the  Amazon  and  the  Orinoco 
are  not  large  enough  to  carry  off  the  surplus  waters.     Hence  their  plains  are  often  flooded. 
West  of  the  Andes,  the  slope  is  abrupt,  and  the  rivers  are  short.     There  are  no  well-defined 
basins. 

50.  In  Africa,  the  principal  river  basins  are  those  of  the  Nile,  the  Livingstone  or 
Congo,  the  Zambeze  (zdm-bd'-za),  and  the  Niger  (nl'-jer).     The  Nile  carries  off  the  surplus 
waters  of  lakes  Albert  and  Victoria,  situated  3,800  feet  above  sea  level.     The  yearly  rise  of 
water  floods  a  large  area  of  the  Nile  valley,  covering  it  with  a  layer  of  rich  soil. 

51.  The  drainage  basins  of  Europe,  though  numerous,  are  much  smaller  than  that 
of  the  Mississippi.     Those  of  the  Volga  and  the  Danube  are  the  largest.     The  basins  of  the 
Rhine  and  the  Rhone  are  the  most  important.     The  principal  divide  of  Europe  occurs  in  the 
plains,  and  is  formed  by  the  slopes  of  the  Valdai  Hills.     The  sources  of  nearly  all  the  large 
rivers  of  Europe,  except  the  Danube,  are  on  the  slopes  of  this  divide. 

52.  In  Asia,  the  slopes  of  the  Stanovoy  and  the  Himalaya  mountains  form  the  chief 
watersheds.     These  mountains  enclose  a  depression  of  land  dotted  with  steppe  lakes,  from 
which  the  rainfall  is  almost  wholly  removed  by  evaporation. 

53.  The  eastern  and  the  southern  surface  slope  to  the  Pacific  and  Indian  oceans  respec- 
tively.    These  slopes  are  drained  by  large  rivers,  the  principal  of  which  are  the  Amoor, 
Hoang,  Yang-tse,  Irrawaddy,  Brahmapootra,  Cambodia,  and  Ganges. 

54.  The  Amoor  river  and  its  basin  are  of  great  importance  to  Russia.     The  valley  of  the 
A  moor  is  fertile,  producing  large  crops  of  grain.     The 

river  is  the  only  great  inland  highway  in  eastern  Russia. 
It  is  navigable  for  1,500  miles. 

55.  The  Yang-tse  Kiang 1  is  also  an  important  inland 
highway  of  eastern  Asia.     It  is  navigable  for  large  ships 
250  miles  from  its  mouth,  and  for  river  steamers,  450  miles 
farther. 

56.  The  Ganges  is  navigable  for  a  distance  of  1,500 
miles  from  its  delta,  and  a  greater  number  of  vessels  ply 
on  its  waters  than  on  any  other  river  in  the  world.     It  dis- 
charges its  waters  through  a  great  net-work  of  channels, 
on  one  of  which,  the  Hoogly  river,  Calcutta  is  situated. 
The  land  about  the  delta  of  the  Ganges  is  low  and  swampy ; 
it  is  called  the  Sunderbunds.2 


1  Ho  and  Kiang  mean  river. 

'2  The  Ganges  is  the  sacred  river  of  India,  and  is  one  of  the  most  celebrated  in  the  world, 
the  valley  of  the  Ganges  has  but  few,  if  any,  equals  in  the  world. 


For  fertility  and  richness. 


74 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


57.  Economy  of  Rivers. — Rivers  are  free  and  natural  highways,  and  as  such,  their 
importance  cannot  be  over  estimated.   Without  a  navigable  river,  the  settlement  of  a  country 
is  usually  slow  and  restricted. 

58.  In  the  growth  and  settlement  of  the  United  States,  rivers  have  always  constituted 
the  pioneer  transportation  lines,  and  have  played  a  most  important  part  in  the  prosperity  of 
the  country.     Therefore,  the  Government  has  wisely  forbidden  the  obstruction  of  navigable 
channels,  and  their  control  is  placed  wholly  in  the  power  of  Congress.1 


WHAT  HAS  BEEH  TAUGHT  IK  CHAPTER  XL 


One-third  of  the  water  falling  upon  the  Earth 
finds  its  ^vay  back  to  the  ocean. 

TJiis  water  collects  in  channels,  called,  accord- 
ing to  their  size,  rills,  rivulets,  brooks,  creeks, 
and  rivers. 

In  the  upper  course  of  a  river,  the  current  is 
rapid,  always  cutting  and  wearing  its  channel 
deeper. 

In  the  middle  course,  it  carries  much  of  the 
lighter  sediment  taken  from  the  upper  portion. 

In  the  lower  course,  the  river  deposits  the  sed- 
iment, building  its  banks  and  bed,  often  extend- 
ing them  some  distance  into  the  sea. 

The  sediment-carrying  power  of  a  river  de- 
pends tvholly  upon  the  velocity  of  its  current. 

In  the  upper  and  the  middle  course,  a  river 
changes  its  channel  but  slightly,  while  in  the 
lower  part,  it  flows  around  the  obstacles  it  has 
deposited  in  its  own  way. 

A  river  system  consists   of  a  river  and   its 


branches  ;  and  a  river-basin,  the  surface  drained 
by  the  river  system. 

The  rim  of  the  basin  forms  a  watershed  or 
divide. 

The  principal  divide  of  North  America  is  that 
from  ivhose  slopes  the  Athabasca,  the  Saskatch- 
ewan, the  Columbia,  and  the  Missouri  river 
radiate. 

South  America  possesses  but  few  well-defined 
drainage  basins,  its  main  watershed  being  the 
Andes  mountains. 

Tlie  chief  drainage  basins  of  Africa  are  those 
of  the  Nile,  Livingstone,  Nigert  and  Zambeze 
rivers. 

The  chief  watersheds  of  Asia  are  the  Hima- 
laya and  the  Stanovoy  mountains,  from  whose 
outer  slopes  the  rivers  flow  in  every  direction. 

The  chief  watersheds  of  Europe  are  the  Valdai 
Sills  and  the  Alps  ;  the  largest  basins,  those  whose 
rivers  flow  into  the  Caspian  and  Black  seas. 


1  To  the  Teacher. — In  the  study  of  hydrographic  basins,  the  following  exercise  will  be  found  an  excellent  one : — 
On  a  good  map  of  the  United  States  draw  a  very  light  pencil  line  which  shall  separate  the  Mississippi  and  its  tribu- 
taries  from  those  rivers  flowing  into  any  other  water  than  the  Gulf  of  Mexico.  This  line  may  enclose  all  rivers  east  of  1he 
Rocky  mountains,  and  all  west  of  the  Appalachian  divide.  In  the  same  manner,  the  chi»  f  hydrographic  basins  of  South 
America  may  be  defined.  In  separating  the  basin  of  the  Orinoco  from  that  of  the  Amazon,  it  must  be  remembered  that  the 
Cassiquiare  river  divides  or  forks,  sending  part  of  its  waters  into  the  Orinoco,  and  part  into  the  Rio  Negro,  a  tributary  of  the 
Amazon.  On  the  map  of  Europe,  from  the  Valdai  Hills  draw  a  line  which  shall  separate  the  rivers  flowing  into  the  Arctic 
ocean,  the  Baltic  and  North  seas  from  those  that  flow  into  the  Mediterranean,  Caspian,  and  Black  seas.  This  line,  which 
should  terminate  at  the  strait  of  Gibraltar,  is  the  principal  divide  between  high  and  low  Europe.  These  lines,  after  being 
inspected  and  corrected  by  the  teacher,  may  be  drawn  with  red  ink. 

The  formation  of  terraces  along  river  valleys  suggests  that  there  have  been  occasional  periods  of  rest  in  the  elevation 
of  continents.  "I  counted  to-day  forty-one  distinct  ledges  or  shelves  of  terrace  embraced  between  our  water-line  and  the 
syenitic  ridges  through  which  Mary  river  forces  itself.  These  shelves,  though  sometimes  merged  into  each  other,  presented 
distinct  and  recognizable  embankments  or  escarps  of  elevation.  This  imposing  series  of  ledges  carried  you  in  forty-one 
gigantic  steps  to  an  elevation  of  480  feet ;  and  as  the  first  rudiments  of  these  ancient  beaches  left  the  granite  which  had 
once  formed  the  barrier  sea-coast,  you  could  trace  the  passing  from  Drift-strewn,  rocky  barricades  to  clearly-defined  and 
gracefully  curved  shelves  of  shingle  and  pebbles.  The  studies  of  these  terraced  beaches  at  various  points  on  the  northern 
coast  of  Greenland  are  more  imposing  and  on  a  larger  scale  than  those  usually  regarded  by  geologists  aa  indicative  of  sec- 
ular uplift  of  coast." — Kane's  Arctic  Explorations. 


AVALANCHES,     GLACIERS,     AND    ICEBERGS. 


CHAPTER      XII. 


,     ai^CIERS, 


ICEBERQS. 


An  Avalanche  in  the  Rocky  Mountains. 


1.  Accumulation  of  Snow.  —  More  snow  falls  between  the 
heights   of   6,000  and   9,000  feet  than   at  any  other   elevations. 
Below  4,000  feet,  but  little  snow  accumulates,  and  only  a  very 
small  amount  falls  above  an  elevation  of  11,000  feet.1 

2.  On  the  Alps,  the  yearly  snow-fall  is  about  sixty  feet  in 
depth.     In  the  Cascade  mountains  of  North  America,  the  snow- 
fall considerably  exceeds  this  amount,  the  snow  often  accumu- 
lating to  a  depth  of  sixty  feet.    • 

3.  Removal  of  the  Snow.  —  Except  on  the  highest  mountain- 
peaks,  the  snow  is  removed  by  the  summer's  heat,  but  in  high 
latitudes,  there  are  large  areas  of  mountain  territory  perpetually 
covered  with  snow.     In  the  latter  case,  it  might  seem  as  though 
the  mountains  would  be  covered  deeper  and  deeper,  until  they 
formed    an   immense    snow-bank   many   times   larger    than   the 
mountain   itself  ;    but  there   are   several   agents   in  nature  that 

combine  to  prevent  this. 

4.  The  great  weight  of  a  snow-drift  is  often 
sufficient  to  melt  it  at  the  bottom,  thus  preventing 
further  accumulation. 

5.  Evaporation    is    another  agent.      Without 
melting,  snow  and  ice  evaporate  just  as  certainly 
as  water  does,  only  not  so  rapidly.      On  the  tops 
of   mountains   where   the    air   does   not    press    so 
heavily,  evaporation  goes  on  much  more  rapidly 
than  at  the  sea-level. 


6.  Wet  clothes  hanging  out-of-doors  soon  dry,   although  they  may  be   frozen   stiff. 
Muddy  roads  that  have  frozen  over,  often  become  dry  and  dusty  without  thawing. 

7.  The  wind  is  another  agent.     On  high  mountain  crags,  the  wind  often  blows  with 
a  velocity  of  100  miles  an  hour.     Such  a  gale  quickly  clears  the  snow  from  all  exposed 
places,  drifting  and  packing  it  solid  in  the  ravines  and  canons. 

8.  The  larger  part  of  the  snow  and  ice  is  carried  down  the  mountain  side  in  the 
form  of  avalanches  or  glaciers. 

9.  Avalanches. — On  account  of  their  position  in  the  center  of  a  thickly  populated 
district,  more  is  known  about  the  avalanches  and  glaciers  of  the  Alps  than  those  of  any 
other  region  in  the  world. 


1  In  the  Frigid  and  Torrid  zones,  however,  the  case  is  different.     In  the  Torrid  zone,  the  limit  of  perpetual  snow  is 
about  16,000  feet  above  the  sea-level.     In  the  Frigid  zone.the  limit  of  perpetual  snow  descends  to  the  level  of  the  ocean. 


76  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 

10.  The    Alpine   peaks,    having    abrupt   slopes,   are    favorable   for   the   occurrence 
of    avalanches.      When    the    mass    of    snow  becomes    so    great    that    it    can    no    longer 
rest  on    the  steep  slopes  of  the  mountain,  there  is  a  sharp  crack ;   a  cleft  in  the  snow- 
field  appears,  and  then  an  immense  mass  of  snow  dashes  down  the  slope  with  terrific 
violence.1 

11.  The  instant  the  avalanche  stops,  the  flakes  of  snow  are  changed  by  the  great 
pressure  to  granules  of  ice.     These  quickly  cohere,  and  the  whole  mass  of  moving  snow 
becomes  instantly  as  solid  as  ice. 

12.  Avalanches  in  the  Alps  occur  with  great  frequency.     Often,  during  a  single  day,  a 
dozen  or  more   will    dash  with  a  low,   sullen  roar  down  the  mountain-side,   sometimes 
burying  villages  and  bearing  fearful  destruction  in  their  course.2    They  are  less  prevalent 
in  the  Rocky  and  Sierra  Nevada  mountains,  because  the  slopes  of  the  latter  are  less  abrupt 
than  those  of  the  Alps. 

13.  Glaciers. — The  snow  which  has  tumbled  down  the  mountain-side  in  the  form  of 
avalanches  and  much  that  has  fallen  in  a  natural  manner  is  removed  in  a  singular  way. 

14.  Winds  gradually  drift  the   snow  into   ravines   and  mountain-valleys.      From 
these,  it  often  extends  into  the  region  of  cultivated  fields  and  far  below  the  altitude  which 
marks  the  limit  of  perpetual  snow. 

15.  If  we  examine  this  mass  of  snow  and  ice,  we  shall  find  that  it  is  moving  slowly 
down  the  ravine  —  sometimes  not  more  than  a  few  inches  a  month,  but  often  twenty  or 
thirty  inches  a  day. 

16.  This  moving  mass  of  snow  and  ice  is  a  glacier.     Its  current,  resembling  that  of 
a  river,  is  swiftest  at  the  surface  and  slowest  at  the  sides  and  bottom.     The  velocity  of  a 
glacier  depends  on  the  temperature  of  the  ice,  the  steepness  of  the  slope,  and  also  the  depth 
of  the  ice.     Twelve  or  fifteen  inches  a  day  is  an  average  rate. 

17.  The  upper  part  of  the  glacier  consists  of  snow  sometimes  more  or  less  compact, 
but  often  as  soft  and  flaky  as  when  it  fell  from  the  clouds. 

18.  Very  soon  after  it  begins  its  journey, the  alternate  thawing  and  freezing  change  the 
snow-flakes  to  small  rounded  grains  of  ice,  called  neve  (nava).     In  time,  much  of  the  neve, 

1  In  these  mountains.the  greatest  accumulation  of  snow  takes  place  at  an  elevation  of  eight  or  nine  thousand  feet,  the 
peaks  which  exten:!  above  this  height  being  quite  bare. 

8  "  Having  crossed  about  three  quarters  the  breadth  of  the  couloir,  the  leading  men  sunk  considerably  above  their 
•waists.  *  *  *  I  tried  to  follow  Bennen,  but  sank  up  to  my  waist.  So  I  went  through  the  furrow,  holding  my  arms 
close  to  my  body  so  as  not  to  touch  the  sides.  As  the  snow  was  good  on  the  other  side,  we  came  to  the  false  conclusion  that 
the  snow  was  accidentally  softer  there  than  elsewhere.  Boisonnet  made  a  few  steps  in  advance,  when  we  heard  a  deep 
cutting  sound.  The  snow-field  had  split  in  two  about  fourteen  or  fifteen  feet  above  us.  The  cleft  was  at  first  quite 
narrow,  not  more  than  an  inch  broad.  An  awful  silence  ensued  :  it  lasted  but  a  few  seconds,  and  then  it  was  broken  by 
Bennen's  voice,  '  Wir  sind  alle  verloren.''  (We  are  all  lost.)  They  were  his  last  words.  *  *  *  The  ground  on  which  we 
stood  began  to  move  slowly.  I  soon  sank  to  my  shoulders  and  began  descending  backwards.  The  speed  of  the  avalanche 
increased  rapidly,  and  before  long  I  was  covered  up  with  snow.  I  was  suffocating,  when  with  a  jerk  I  suddenly  came  to 
the  surface  again.  It  was  the  most  awful  sight  I  ever  witnessed.  Around  me, I  heard  the  horrid  hissing  of  the  snow,  and 
far  before  me  the  thundering  of  the  foremost  part  of  the  avalanche.  At  last,  I  noticed  that  I  was  moving  more  slowly ; 
then  I  saw  the  pieces  of  snow  in  front  of  me  stop,  and  I  heard,  on  a  large  scale,  the  same  creaking  sound  that  is  produced 
when  a  heavy  cart  passes  over  hard  frozen  snow.  I  felt  that  I  had  stopped,  and  threw  up  my  hands  to  protect  my  head, 
*  *  *  but  was  covered  up  with  the  snow  coming  behind  me.  I  made  vain  efforts  to  extricate  my  arms,  but  found  it 
impossible.  *  *  *  A  sudden  exclamation  of  surprise !  Rebot  had  seen  my  hands.  *  *  *  I  was  at  length  taken 
out :  the  snow  had  to  be  cut  with  an  axe  down  to  my  feet  before  I  could  be  pulled  out." — TYNDALL. 


AVALANCHES,     GLACIERS,     AND    ICEBERGS. 


77 


by  the  constant  pressure  of  its  par- 
ticles, loses  the  air  it  had  contained 
and  becomes  welded  into  solid  ice. 

19.  Crevasses.  —  Numerous  fis- 
sures, called  crevasses,  are  formed 
in  a  glacier  by  irregularities  in  its 
course,  in  the  inclination  of  its  bed, 
and  in  the  velocity  with  which  it 
moves.1 

20.  Moraines.  —  Rocks    which 
have  been  broken  from  the  cliffs, 
together  with  stones,   gravel,   and 
other  materials  which  have  rolled, 
or  fallen,  upon  the  glacier  are  car- 
ried along  with  it.     Such  accumula- 
tions are  called  moraines. 

21.  Those  which  are  at  the  sides 
of  the  glacier  are  called  lateral  mo- 
raines.    Viewed  from  the  glacier, 
they  resemble  long  walls.      When 
two  glaciers  enter  the  same  valley, 
their  moraines  which  meet  and  are 
carried  thence  along,  or  near,  the 
center  of  the  main  glacier,  form  a 
medial  moraine. 

22.  The  great  mass    of   stones, 
gravel,  and  other  materials  which 
have  been  deposited  at  the  end  of  a 
glacier,  is  called  a  terminal  moraine. 
It  sometimes  covers  an  area  of  more 
than  a  square  mile  and  exceeds  a 
hundred  feet  in  height. 

23.  A  river  issues  from  the  lower 
end  of  a  glacier.    The  Rhine,  Rhone, 
Po,  and  a  number  of  the  tributaries 
of  the  Danube  have  their  sources 
among  the  Alpine  glaciers.2 


An  Alpine  Glacier.     The  beginning  of  a  river. 


1  The  velocity  with  which  a  glacier  moves  is  greater  in  the  center  than  at  the  sides,  and  at  the  surface  than  at  the 
bottom.      It  is  greater  in  summer  than  in  winter,  and  in  mid-day  than  at  night.     The  greater  the  slope  of  the  J>ed,  the 
greater  is  the  velocity. 

2  The  glaciers  of  the  Alps  have  their  sources  far  above  the  snow-line,  while  their  terminal  moraines  are  about  5.UUO 
feet  below  it.     The  snow-line  on  the  Alps  is  about  9,003  feet  above  the  level  of  the  sea.     For  the  formation  of  glaciers,  it  is 
necessary  that  the  mountains  extend  above  the  snow-line,  and  that  there  be  alternate  freezings  and  thawings. 


78 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


24.  The    water    issuing    from   the 
lower   end    of    a    glacier    is    always 
muddy,  because  it  contains  substances 
that  are  worn  from  the  bottom  and 
the  banks  of  the  ravine. 

25.  Distribution. — There  are  many 
large  glaciers  in  the  Himalaya  moun- 
tains, but  they  are  comparatively  un- 
known.    The  glaciers  of  Mts.  Eainier 
and  Shasta  in  the  United  States  are 
equal  in    size   to   the  largest  Alpine 
glaciers. 

26.  By  far  the  largest   glaciers  in 
the  world  are  those  of  Greenland  and 
Alaska.     Humboldt  glacier  in  Green- 
land   is    said    to    be    sixty    miles    in 
breadth. 

27.  Icebergs. — Icebergs  are  masses 
of   ice  broken   from   glaciers,   where 
the  latter  terminate  on   a   sea-coast. 
The    end    of    the    glacier    is    pushed 
into  the  water  until  a  large  mass  is 
broken  off. 

28.  The  mass  of  ice  thus  broken 
off  floats  along  with  some  ocean  cur- 
rent, until  it  is  melted  by  the  warmer 
water  into  which  it  floats. 

Floating  Iceberg. 

29.  Icebergs  from   the   Greenland 

glaciers  drift  southward  in  the  Arctic  current,  through  Baffin  Bay.     Near  Newfoundland, 
they  meet  the  warm  water  of  the  Gulf  Stream  and  drift  between  the  opposing  currents 
until  they  are  melted. 

30.  It  is  thought  by  many  geographers  that  the  banks  or  shallows  east  of  the  gulf 
of  St.   Lawrence  have  been    formed    by   the    sand,   gravel,   and   boulders,   carried   there 
by  means  of  icebergs  which,  on  melting,  drop  their  load  to  the  bottom  of  the  sea. 

31.  From    an    eighth   to  a  tenth   of    the   iceberg   is   above  water,   the    remainder 
being  below  the  surface.      On  one  or  two  occasions,  icebergs  projecting  a  thousand  feet 
above  water,  have  been  observed  ;•  but  ordinarily,  they  seldom  exceed  one  or  two  hundred 
feet  in  height  above  the  surface. 

32.  Ancient  Glaciatioii. — The  transporting  power  of  glaciers  is  wonderful.     A  wide 
stretch  of  country  between  the  Baltic  and  the  Black  sea  is  covered  with  boulders  and 
drift,    carried    from    the    Scandinavian    mountains    by   glaciers    of    a    former    geological 
period. 

33.  Portions   of   England   and   Scotland   are  also    covered  with   similar  drift,   called 
"till."    These  boulders  are  distinguished  by  their  faces,  which  are  ground  flat  and  scored 
with  parallel  scratches. 


AYALANCHES,     GLACIERS,     AND    ICEBERGS. 


79 


34.  In  examining  that  part  of  Europe  which  comprises  the  Scandinavian  peninsula, 
Oreat  Britain,  and  Ireland,  one  cannot  help  noticing  the  frayed  and  ragged  appearance 
of  their  western  coasts. 

35.  These  notches  in  the  coast  are  the  work  of  glaciers  which,  originating  in  the  higher 
portions  of  the  Scandinavian  mountains,  furrowed  and  scraped  the  surface  of  northwestern 
Europe  into  its  present  shape. 

36.  In  North  America,  the  work  of  glaciers  has  been  of  even  greater  magnitude. 
Here,  the  ice-flood  came  from  the  north  and  extended  as  far  south  as  the  Ohio  river. 

37.  The  peculiar  shape  of  most  of  the  older  North  American  lakes  is,  by  many  geologists, 
attributed  to  glacial  action. 

38.  Observe  that  those  of  the  northern  and  northeastern  part,  especially,  are  long  and 
very  narrow.     Their  lines  of  greatest  length  are  usually  parallel ;  but  occasionally,  a  group  of 
lakes,  like  those  of  central  New  York,  are  ranged  like  the  spokes  of  a  wheel  and  point  to 
a  common  center. 

39.  Late   researches   have   shown  that   lakes   occur  chiefly   in   regions  covered  with 
glacial  boulders,  and  that  they  are  comparatively  rare  in  those  parts  of  the  Earth  that  are 
free  from  glacial  action. 


WHAT    HAS    BEEN    TAUGHT    IK    CHAPTER    XII. 


The  greatest  amount  of  snow  falls  between 
the  altitudes  of  6,OOO  and  .9,000  feet;  little 
falls  above  the  latter  altitude. 

This  accumulation  of  snow  is  removed  by 
wind,  avalanches,  glaciers,  evaporation,  and  by 
'melting. 

On  account  of  the  abrupt  slopes  of  the  mount- 
ains, avalanclies  are  most  frequent  in  the  Alps, 
<ind  they  usually  take  place  just  after  heavy 
•snow-storms. 

The  snow  brought  down  the  mountain  side 
by  avalanches  and  drifted  into  the  canons  by 
the-  wind,  forms  glaciers. 

The  motion  of  a  glacier  resembles  that  of  a 
river,  being  greatest  at  the  center  of  £ts  upper 
surface  and  slowest  at  the  bottom  and  the  sides. 

The  source  of  a  glacier  is  fine  snow,  called 
neve,  ivhich  is  converted  by  pressure  into  ice. 

The  glacier,  in  its  central  and  lower  parts, 
•is  seamed  with  crevasses,  extending  partly  or 
wholly  across  it. 

The  rocks,  gravel,  and  earth  which  are 
piled  up  at  the  sides  of  the  glacier,  or  per- 
haps pushed  along  before  it,  constitute  its 
moraines. 


The  lower  end  of  a  glacier  usually  forms 
the  source  of  a  river.  Most  of  the  rivers  of 
central  Europe  and  many  of  those  in  Asia 
originate  in  this  manner. 

Glaciers  occur  in  the  Himalaya,  the  Rockyt 
and  many  other  mountain-ranges,  the  largest 
in  the  world  being  those  of  Greenland  and 
Alaska. 

Icebergs  are  masses  of  ice  broken  from  gla- 
ciers which  terminate  on  the  shores  of  polar 
regions. 

The  icebergs,  broken  from  glaciers  of  Green- 
land, drift  southward  with  the  Arctic  current 
until  they  meet  the  warm  waters  of  the  Gulf 
Stream. 

Various  parts  of  the  world  are  strewn  with 
boulders,  left  by  glaciers  during  past  geolog- 
ical ages. 

Tfie  configuration  of  northwestern  Europe, 
as  well  as  its  notched  and  ragged  coast  lines, 
are  due  to  glacial  action. 

In  North  America,  there  are  evidences  of 
glacial  action  as  far  south  as  the  Ohio  river. 

The  lakes  of  the  nortJiern  part  of  North 
America  are  often  attributed  to  glacial  action. 


80 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


OCEAN    WATERS. 


81 


CHAPTER     XIII. 


WA.TERS. 


1.  Area  and  Extent.  —  Of  the  M4,000,000  square  miles  of  the  Earth's  crust  covered  by 
water,  three-fifths  lie  south  of  the  equator,  and  the  remainder  north  of  it. 

2.  Included  in  this  area,  are  two  million  square  miles  about  the  North  Pole  and  eight 
million  square  miles  at  the  South  Pole,  concerning  which  little  is  known.     It  cannot  be  told 
whether  these  desolate  fields  of  ice  rest  upon  land  above  the  ocean  level  or  not. 

3.  Divisions.  —  The  water  surface  of  the  Earth  is  divided  into  five  great  oceans  called 
the  Pacific,  Atlantic,  Indian,  Antarctic,  and  Arctic  oceans  ;  their  areas  are  as  follows  : 


Pacific about  70,000,000  square  miles. 

Atlantic "     35,000,000 

Indian "     28,000,000 


Antarctic about  8,000,000  square  milea. 

Arctic "     2,000,000  " 

Inland  Seas "     1,000,000 


4.  These  divisions  are  all  parts  of  one  great  ocean.    There  are  no  boundaries  sep- 
arating one  from  another,  and  excepting  the  Arctic  ocean,  not  one  of  them  is  landlocked. 

5.  The  Pacific  ocean  has  the  shape  of  an  oval,  bounded  on  the  south  by  the  ice  fields 
of  the  South  Frigid  zone.      Its  eastern  shore  forms  a  long  and  almost  unbroken  line.      It 
encloses  the  submarine  plateau  of  Oceanica. 

6.  The  Atlantic  ocean  is  a  wide  channel  between  the  eastern  and  western  continents. 
Its  two  shore  lines  are  nearly  parallel,  the  projections  of  one  lying  opposite  to  the  indenta- 
tions of  the  other.     The  shores  of  the  northern  part  are  noted  for  their  many  inlets. 

7.  The  Indian  ocean  is  an  immense  gulf,  partly  enclosed  by  Africa,  Asia,  and  Aus- 
tralia.    Its  shore  line  is  broken  by  a  number  of  important  peninsulas. 

8.  Color  of  Ocean  Waters. — The  color  of  the  ocean  varies  in  different  places.     Water 
more  than  sixty  fathoms  deep  is  blue  ;  shallower  water  is  generally  green.     The  amount  of 
mineral  salts  also  affects  the  color  of  ocean  waters.     Fresher  waters  are  a  pale  green,  while 
those  containing  a  greater  proportion  of  salt  are  dark  blue.1 

9.  In  warm  latitudes,  the  ocean  waters  sometimes  glow  with  a  pale  light,  such  as  is 
noticed  when  matches  are  rubbed  in  the  dark,  with  moistened  fingers.     This  phenomenon, 
known  as  phosphorescence,  is  caused  by  various  minute  animalcules. 

10.  The  Antarctic  and  Arctic  oceans  are  comparatively  unknown  regions,  being  almost 
covered  with  ice.     In  each  of  these  oceans,  ice  forms  to  an  average  depth  of  seven  feet 
during  the  winter.     This  amount  is  about  what  the  sun  is  capable  of  melting  during  the 
summer.     There  are,  however,  millions  of  square  miles  covered  with  ice  which  never  melts.2 


1  The  Red  sea,  the  Arabian  sea,  and  the  Gulf  of  California  are  tinged  with  red  ;  the  waters  of  the  Persian  Gulf  are 
now  and  then  of  a  greenish  hue  ;  while  occasionally  there  are,  especially  in  the  Indian  ocean ,  great  bodies  of  water  having  a 
milk-white  appearance.  These  colors  are  due  to  the  presence  of  animalcules,  or  else  to  microscopic  sea  weeds. 

4  Late  researches  render  it  probable  that  the  ice  caps  at  the  poles  have  formed  upon  islands,  gradually  spreading  until 
a  continuous  sheet  of  ice  of  unknown  thickness  has  accumulated. 


MONTEITH'S    FEW    PHYSICAL     GEOGRAPHY. 


11.  The  Bed  of  the  Ocean. — The  bed  of  the  ocean  consists  of  extensive  plains  and 
plateaus.     Wherever  submarine  mountain  chains  occur,  they  are  near  some  continental 
coast.     The  shores  and  nearly  all  shoals  are  usually  strewn  with  fine  sand. 

12.  Temperature. — The  temperature  of  the  ocean  varies  both  with  latitude  and  depth. 
Within  the  tropics,  the  surface  temperature  is  about  80°  F.     In  the  polar  regions,it  does  not 
vary  much  from  28°  F. 

13.  Below  the  depth  of  600  feet, the  temperature  is  not  affected  by  the  heat  of  the  sun  ; 

and  except  where  influenced  by 
warm  ocean  currents,  it  decreases 
uniformly  to  35°  F.,  from  which  it 
varies  but  two  or  three  degrees. 

14.  Where  the  bed  of  the  ocean 
is  not  affected  by  waves  or  currents, 
it  is  covered  with  ooze,  a  substance 
consisting  of  the  shells,  skeletons, 
and  the  insoluble  parts  of  minute 
sea  organisms.     The  ooze  covers  the 
bed  of  the  ocean  in  many  places  to  a 
great  depth. 

15.  Mineral  Salts. — Ocean  wa- 
ters contain  an  average  of  3.4  per 
cent,  of  mineral  substances,  of  which 
common  salt  is  the  chief.     The  fol- 
lowing table  shows  the  composition 
of  the  mineral  salts  in  every  1,000 
parts  of  sea  water. 

Sodium  chloride  (Salt) 27.0 

Potassium  and  Magnesium  chlorides. .  5.8 

Magnesium  and  Lime  sulphates 21 

Lime  carbonate 1 

Iodine,  Bromine,  and  other  substances.  3.0 

16.  The  percentage  of  min- 
eral salts  varies  in  different  local- 
ities.    In  parts  of  the  Arctic  ocean, 

the  salt  is  almost  imperceptible.  In  the  Baltic  sea,  the  water  contains  but  two  per  cent., 
while  in  the  Red  Sea,  which  lies  under  a  tropical  sun,  there  are  4.3  parts  of  salt  in  every 
100  of  water. 

17.  Additional  supplies  of  mineral  salts  are  constantly  conveyed  by  the  waters  of  rivers 
which,  flowing  into  the  sea,  deposit  there  the  mineral  salts  which  they  have  dissolved  from 
the  soil.  These  salts,  therefore,  accumulate  in  the  ocean,  and  mostly  remain  dissolved.  The 
carbonate  of  lime,  however,  is  appropriated  about  as  rapidly  as  it  is  supplied,  by  shell-fish 
and  other  sea  animals  whose  skeletons  are  composed  of  that  substance.1 

1  The  chalk  cliffs  of  England,  much  of  the  limestone  of  the  Mississippi  valley,  and  the  coral  reefa,  have  all  been  formed 
in  this  manner.  Fresh  river  waters  contain  salt  and  carbonate  of  lime  in  about  equal  proportions.  In  ocean  waters,  how- 
ever, there  are  270  parts  of  salt  to  1  part  of  carbonate  of  lime. 


The  Frozen  Zone. 


OCEAN     WATERS. 


83 


CONTOUR  MAP,  SHOWING  PROPORTIONATE  HEIGHTS  OF  LAND  AND  DEPTHS  OF  WATER. 


180          160  Longitude  West  120  from  Greenwich.  80 


20  lonirftuaelEast  60 


From  the  Sea-level  to  500  feet '         i     600—2000  feet  i         i     above  2000  feet  I         I 
Depth  In  fathoms:  under  1000 1         I      1000-2000  I         I     2000-3000  I 1     3000  and  below 

18.  Depth. — The  average  depth  of  the  ocean  is  about  16,000  feet.     Whenever  deeper 
soundings  are  met  with,  the  area  over  which  they  extend  is  not  a  large  one;  and  except  along 
the  shores  of  continents, the  variations  in  depth  are  slight.1 

19.  The   depth   of  the  Atlantic  varies  in  different  parts ;   near  the  western  side  it 
is   19,000  feet.     Between  the  two  continents,  there  is  a  well-defined,  submarine  highland 
known  as  the  "telegraphic  plateau,"  on  which  the  water  is  about  10,000  feet  deep.2 

20.  Along-  the  American  coast,the  bed  of  the  Atlantic  consists  of  several  well-defined 
terraces.     The  first  of  these  is  about  100  miles  in  width,  having  an  average  depth  of  less 
than  1,000  feet.     At  the  edge  of  the  terrace,  the  bed  descends  almost  precipitously  to  a  depth 
of  9,000  feet.     It  then  gradually  descends  to  about  16,000  feet. 

21.  The  depth  of  the  Pacific  and  Indian  oceans  is  the  same  as  that  of  the  Atlantic 
—16,000  feet.     The  soundings  made  in  the  Arctic  ocean  indicate  a  very  slight  depth  ;  those 
of  the  Antarctic  are  much  greater. 


1  By  measuring  the  breadth,  height,  and  velocity  of  waves,  mathematicians  are  able  to  determine  the  average  depth 
of  the  ocean.  In  late  years, the  soundings  made  with  steel  wire  confirm  the  calculated  depths. 

'*  This  plateau  extends  from  the  Azores  to  Iceland,  and  divides  the  bed  of  the  north  Atlantic  into  two  valleys.  The 
depth  of  water  on  the  plateau  nowhere  exceeds  12,000  feet,  and  is  generally  about  9,000  feet!  The  depth  of  the  eastern  valley 
varies  from  12,000  to  15,000  feet,  and  has  been  traced  as  far  south  as  the  Cape  of  Good  Hope.  The  western  valley  has  a  more 
uneven  surface  and  contains  a  greater  depth  of  water.  / 


84 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY, 


600        2,4uu        9,uou  14,UUU  9.UUU  14,400  K',000  6,000 

Section  of  the  Atlantic  Ocean  between  Newfoundland  and  Ireland.    The  figures  show  the  depth  in  feet. 

22.  Inland  seas  and  land-locked  waters  are  always  shallow.     The  Gulf  of  Mexico  and 
the  Mediterranean  sea  vary  in  depth  from  7,000  to  10,000  feet.     The  Red  Sea  is  about  3,000 
feet  deep ;  the  Baltic  and  North  seas,  about  GOO  feet.     The  depth  of  Bering  Strait  does  not 
exceed  150  feet. 

23.  The  deepest  soundings  have  been  made  off  the  eastern  coasts  of  the  continents. 
East  of  the  Kurile  islands,  a  sounding  of  27,930  feet,  and  southeast  of  Newfoundland,  one  of 
27,480  feet,have  been  recorded.     Deeper  soundings  than  these  have  been  reported,  but  they 
are  not  considered  trustworthy.1 

24.  Waves. — The  surface  of  the  ocean  is  never  at  rest.     Even  when  it  is  not  lashed 
into  billows  by  the  wind,  it  is  constantly  heaving  in  long,  gentle  swells. 

25.  Waves  are  caused  usually  by  the  wind.     They  consist  of  the  alternate  rising  and 
falling  of  successive  ridges  of  water.     In  deep  water,  although  the  wave  moves  forward,  the 
water  does  not ;  its  only 'motion  is  the  rising  and  falling. 

26.  This  is  apparent  when  the  wind  blows  over  a  field  of  grain.     Each  stalk  bends 
before  the  gust,  but  immediately  straightens,  while  an  instant  later,  the  grain  just  ahead 
bends  and  straightens.     Thus  the  wave  passes  over  the  field. 

27.  In  shallow  water,  however,  the  motion  of  the  wave  at  its  lower  part  is  retarded 
by  friction  against  the  bottom.     This  causes  the  top  of  the  wave  to  comb  or  roll  forward  and 
break  into  foam. 

28.  The   size   of  a  wave  de- 
pends somewhat  on  the  depth  of  the 
water.     No    large  waves    form   in 
water  less  than  200  feet  deep. 

29.  In   deep    seas,    during  a 
fair  breeze,  the  waves  are  about  six 
feet  in  height  from  trough  to  crest, 
and  sixty  in  breadth.    Waves  of  this 
size  have  an  average  velocity  of  nine 
miles  an  hour  ;  during  a  severe  gale, 
the  velocity  of  waves  sometimes  ex- 
storm  waves.                                              ceeds  twenty-five  miles  per  hour. 

30.  During  a  severe  gale,  the  top  of  a  wave  moves  faster  than  its  lower  part.  In  con- 
sequence, the  waves  break  and  the  sea  is  covered  with  white-caps,  or,  in  very  severe  storms, 
is  lashed  into  foam. 

1  These  soundings  are  as  reported  by  Commodore  George  E.  Belknap,  when  commander  of  the  United  States  steamer 
"Tuscarora."  Prior  to  the  adoption  of  steel  wire,  rope  was  used  for  deep  sea  soundings.  Soundings  made  in  this  manner 
are  now  considered  wholly  untrustworthy.  By  the  late  methods,  not  onlv  are  specimens  of  the  bottom  secured,  but  the 
temperature  at  any  depth  may  also  be  registered. 


OCEAN    WATERS. 


85 


31.  The  waves  do  not  reach  their  greatest  height  until  the  storm  lulls, 
waves  of  forty,  fifty,  and  even  sixty  feet  in  height  have  been  observed, 
such  large  waves  sometimes  exceeds  four  hundred  feet. 


In  deep  water, 
The  breadth  of 


32.  Force  of  Waves. — The  force  with  which  waves  beat  against  the  shore  is  almost 
beyond  belief.     A  wave  moving  with  ordinary  velocity  strikes  a  blow  of  610  pounds  per 
square  foot ;  but  in  severe  storms,  the  striking  force  often  exceeds  6,000  pounds  upon  every 
square  foot  of  surface. 

33.  The  lighthouse  on  Minot's  ledge,  near  Boston,  has  been  thrice  destroyed  by  storms, 
the  last  time,  in  1857.     Although  it  was  built  of  solid  iron  piles  ten  inches  in  diameter,  the 
combined  force  of  wind  and  wave  swept  it  away.     Not  a  vestige  of  the  structure  has  ever 
been  found. 

34.  The  form  of  the  New  England  coast  is  very  largely  the  work  of  waves.     These  wear 
away  the  softer  rock  and  the  tides  carry  off  the  debris.     The  reefs  and  rocky  islands  along 
the  shores  are  the  remnants  of  former  coast  lines. 


WHAT  HAS  BEEN  TAUGHT  IN  CHAPTER  XIII. 


TJiree-fifths  of  the  ocean,  waters  He  south,  and 
the  remainder  north  of  the  Equator. 

It  is  not  definitely  Known  whether  the  regions 
<ibout  the  poles  are  land,  or  water,  chiefly . 

The  Pacific  is  the  largest  ocean,  being  about 
1 trice  the  size  of  the  Atlantic,  and  nearly  as  large 
us  the  remaining  four  divisions  together. 

lit  the  Arctic  ocean,  ice  forms  to  an  average 
thickness  of  seven  feet  during  the  •winter,  and 
much  of  this  ice  remains  throughout  the  year. 

The  bed  of  the  ocean  is  diversified  with  pla- 
teaus and  plains. 

The  best  known  submarine  plateau  is  in  the 
Atlantic  ocean,  midway  betiveen  the  eastern  and 
•western  continents. 

The  average  depth  of  the  larger  oceans  is 
about  16,OOO  feet,  or  three  miles. 

The  depth  of  land-locked  oceans  and  inland 
seas  is  never  great,  and  seldom  exceeds  3?OOO 
feet. 

The  water  of  the  ocean  contains  various  min- 
eral salts  in  solution,  the  principal  of  which  is 
common  salt. 

The  amount  of  salt  varies  from  'two-tenths 
per  cent,  in  the  polar  oceans  to  four  and  three- 
tenths  per  cent,  in  the  Red  Sea. 


The  surface  of  the  ocean  is  never  at  rest,  but 
is  constantly  tossed  ivith  waves  or  gentle  swells. 

Waves  are  the  alternate  rising  and  falling  of 
successive  ridges  of  water  upon  the  surface  of 
the  sea. 

The  wave  has  a  progressive  motion,  but  the 
water  has  not. 

The  height  of  the  wave,  usually  about  one- 
tenth  its  breadth,  depends  chiefly  on  the  depth 
of  water. 

With  a  fair  breeze,  deep  water  waves  are  about 
sixty  feet  broad  and  six  feet  high.  Their  velocity 
is  eigJit  or  nine  miles  per  hour. 

The  velocity  of  storm  waves  sometimes  exceed* 
twenty  miles  an  hour. 

The  breaking  of  waves  occurs  wherever  the 
crest  of  the  wave  moves  faster  than,  the  lower 
part. 

The  waves  run  highest  at  the  lulling  of 
the  storm.  Then  they  are  sometimes  sixty  feet 
in  height  and  four  or  five  hundred  feet  in 
breadth. 

The  force  with  which  a  wave  strilces  varies 
from  6OO  pounds  to  the  square  foot  in  ordinary 
weather,  to  fi,OOO  pounds  to  the  square  foot  dur- 
ing severe  storms. 


86 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


CHAPTER      XIV 


TIDES. 


The  figures  show  the  tilM  of  Kign  wat 
at  new  and  full  moon  along  the  courtet 

the  linet. 


100  180  140  160  180          ItO  Longitude  West  120  from  Greenwich  80 


80  lx>ngltuaeEaat  60 


CHAKT  OF  CO-TTDAI,  LIHES. 

The  blue  lines  in  the  Chart  show  the  position  and  the  direction  of  the  crest  of  the  tide-wave  for  each,  hour  of  the  d»".     It  Is  seen 
that  the  direction  of  the  theoretical  wave  exists  only  in  the  broadest  expansion  of  the  ocean. 

1.  Movements    of  Ocean   Waters.  —  There    are  two  movements  of    ocean   waters 
which  are  regular  and  constant ;  they  are  tides  and  ocean  currents. 

2.  Tides  are  immense  waves  which,  in  mid-ocean,  are  about  three  feet   in   height 
and  several  thousand  miles  in  breadth. 

3.  An  observer  standing  on  the  sea  shore,  will  notice  that  the  level  of  the   water 
is  not  always  the  same.      For  six  hours,  it  reaches  higher  and  higher  upon  the  beach. 
Then  it  ceases  to  rise;  and  after  a  few  moments,  begins  to  recede.      It  continues  to  fall 
for  six  hours,  when  the  waters,  after  remaining  stationary  for  a  few  moments,  again 
begin  to  rise.1 

1  The  rising  of  the  water  is  called  the  "flood,"  and  the  falling-,  the  "ebb"  of  the  tide.  The  periods  of  greatest 
elevation  and  depression  are  known  as  "  high  water "  and  "  low  water,"  respectively ;  that  of  the  cessation  of  the 
current,  "slack  water." 


TIDES. 


87 


4.  The  cause  of  this  rising  and  falling  of  water  is  ascribed  to  the  attraction  which 
the  sun  and  moon  exert  upon  the  waters  of  the  Earth. 

5.  Gravitation. — Both  the  sun  and  the  moon  attract  the  'Earth.    But  while  the  crust 
of  the  Earth,  being  rigid,  does  not  noticeably  bend,  the  water  is  drawn  in  an  elongated 
or  lemon-shaped  form,  on  account  of  which  it  appears  to  be  massed  toward  the  attracting 
bodies,  as  you  see  in  the  diagram  below. 

6.  High  water  does  not  occur  when  the  moon  is  directly  over- 
head, but  several  hours  afterward.  In  other  words,  the  tide-waves, 
owing  to  friction  against  the  bottom  of  the  ocean,  cannot  quite 

keep  pace  with 
the  moon,   and 
therefore       lag 
M{   !llllli<-«Al  EARTH   •     behind. 


Moon  in  Conjunction,  or  between  the  Earth  and  Sun. 


7.  The  tide- 
waves  are  high- 
est in  the  trop- 
ics, and,  except 

where  the  shores  of  continents  cause  local  irregularities,  their  height 

diminishes  in  the  direction  of  the  poles. 

8.  Not  only  is  the  water  drawn  into  an  ovoid  form,  but  the  Earth,  also,  is  pulled 
towards  the  moon.  This,  in  effect,  gives  the  appearance  of  two  waves,  one  on  each  side 
of  the  Earth.1 

9..  Moon  in  Conjunction.— When  the  sun  and  moon  have  the  relative  position  shown 
in  the  accompanying  diagram,  it  is  evident  that  their  combined  attraction  will  produce  a 
tide-wave,  having  a  much  greater  height  than  the  attraction  of  either  body  alone.  In 
this  position,  the  moon  is  said  to  be  in  conjunction. 

10.  Moon  in  Opposition.— Even  though  the  sun  and  the 

moon   are    on    opposite   sides   of   the    Earth,   their    combined 
attraction  being  in  the  same  line,  forms  a  tide-wave  as  high 


Moon  in  Opposition,  or  on  the  side  of  the  Earth  furthest  from  the  Sun. 

as  though   both  were  on   the   same  side.      When   the  moon 
is  on  the  side  of  the  Earth  furthest  from  the  sun,  as  you 
see  in  the  diagram,  it  is  said  to  be  in  opposition. 


1  This   theory  of   the  formation  of  the   tide-wave   on   the    opposite   side  of  the   Earth  is  not  accepted  by  all 
scholars. 


88  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 

11.  Moon  in  Quadrature. — But  if  the  moon  is  in  the  position  shown  in  the  fol- 
lowing diagram,  the  sun  and  the  moon  exert  their  attractive  force,  each  in  a  different 
direction.     In  this  position,  the  moon  is  said  to  be  in  quadrature. 

12.  Four   tide- waves   a  day  will  take  place  at  such  times  —  two  formed  by  the 

sun,  so  slight  as  to  be  hard- 
ly noticeable,    and  two  by 
IM          the  moon,  each  of  which  is 
A  smaller  than  when  both  the 

*  sun  and  the  moon  exert  a 

combined  attraction. 

13.  The  tide-wave  formed 
by  the  sun,  however,   is   a 
few  inches  only  in  height. 
In    using   the    term    "tide- 
Moon  m  Quadrature.  wave,"  the  wave  caused  by 

the  moon  is  always  meant. 

14.   Spring   and   Neap  Tides. — Tides  occurring  at  new  and 
at   full   moon — or  when   the  moon   is    either  in  opposition   or  in 

conjunction — are  called  spring  tides;  those  occurring  when  the  moon  is  in  quadrature 
are  neap  tides. 

15.  Course  of  the  Wave. — The  two  tide-waves  thus  formed  on  opposite  sides  of  the 
Earth,  accompany  the  moon  and  pass  around  the  Earth,  each  in  about  twenty-eight  days. 
But  while  the  two  waves  are  journeying  around  the  Earth,  the  latter  is  turning  in  the  same 
direction  upon  its  axis  every  twenty-four  hours. 

16.  Therefore,  instead  of  two  tides  a  month,  there  are  two  tides  a  day.    Each  day,  the 
tide  is  at  flood-height  about  fifty  minutes  later  than  on  the  preceding  day.1 

17.  Effect    of  Land   Masses.  —  In*  the  foregoing  description,  it  has  been  assumed 
that  the  surface  of  the   Earth  is  evenly  covered  with  water.     The  motion  and  direction 
of  the  tide- waves  are  greatly  modified  by  the  continents.     Especially  is  this  the  case  in  the 
northern  hemisphere,  for  here  the  actual  tide  conforms  but  slightly  to  the  theoretical. 

18.  The  tides,  instead  of  having  a  uniform  height  of  two  and  one-half  or  three  feet, 
as  in  mid-ocean,  are  in  the  North  Temperate  zone  about  four  feet,  although  they  sometimes 
exceed  sixty  feet. 

19.  Local  High  Tides. — In  the  Bay  of  Fundy,  the  tide  rises  to  a  height  of  from  fifty 
to  eighty  feet.     The  reason  for  this  excessively  high  tide  is  the  shape  of  the  coast,  and  its 
position  with  respect  to  the  direction  of  the  wave. 

20.  By  looking  at  the  map,  you  will  notice  that  the  tide- wave  of  the  northern  Atlantic 
travels  in  a  northerly  direction.     The  coast  of  Nova  Scotia  and  the  shores  of  the  Bay  of 
Fundy  have  the  shape  of  a  A,  which  faces  the  south. 

1  The  pupil  must  bear  in  mind  that  the  two  tide-waves  with  reference  to  the  moon  are  stationary — that  is,  they  revolve 
around  the  Earth  just  as  though  they  were  fastened  to  the  moon.  The  daily  tides  are  caused  by  the  Earth  turning  on 
its  axis  within  the  tide- waves.  Consequently,  an  observer  overtakes  and  passes  the  two  waves  daily. 


TIDES. 


89 


21.  Into  this  bay,  the  tide-wave  rushes  with  a  terrific  roar,  and  as  the  water  cannot 
spread  out,  it  must  rise  all  the  higher.     In  many  estuaries,  the  bore  or  egre  thus  formed 
is  a  wave   twenty  or   thirty  feet    in   height,  moving  with  a  velocity  of   fifteen   miles 
an  hour. 

22.  All  V-shaped  bays  and  estuaries  which  face  the  tide-wave  have  very  high  tides. 
At  the  mouth  of  the  Hoogly,  one  of  the  branches  of  the  Ganges  river,  and  in  various  inlets 
of  the  Indian  Ocean,  the  tide  often  rises  to  a  height  of  forty  feet  or  more.1 

23.  Inland  seas  do  not  usually  have  a  noticeable  tide,  though  there  are  a  few  remark- 
•able  exceptions.     Thus,  while  the  tide  of  the  Mediterranean  is  hardly  perceptible,  that  of 
the  Adriatic  (ad-re-dt'ic)  is  between  one  and  two  feet  in  height.    The  tides  of  the  Red  Sea 
are  often  six  feet  in  height. 

24.  This  difference  in  the  tide-level  is  especially  great  on  the  shores  of  the  isthmus 
of  Panama.    Here,  the  tide  of  the  Atlantic  ocean  is  scarcely  apparent ;  that  of  the  Pacific 
is  between  twenty-five  and  thirty  feet. 

25.  The  erosive  power  of  tides  is  very  great.    By  their  action,  bays  are  formed,  and 
channels  are  quickly  cleared  of  the  sediment  and  debris  scoured  from  the  coast  shores. 


WHAT  HAS  BEEN  TAUGHT  ffl  CHAPTER  XIY. 


Tides  are  waves  about  1O,OOO  miles  in 
breadth,  and  in  mid-ocean  about  three  feet 
in  height. 

Two  of  these  waves  occur  daily,  each  wave 
•requiring  about  twelve  hours  in  its  rise  and 
fall. 

TJie  cause  of  the  tide-waves  is  thought  to  be 
the  attractive  force  of  the  moon  and  the  sun. 

When  the  sun  and  the  moon  are  in  conjunc- 
tion, or  in  opposition,  the  tides  reach  their 
height. 

When  the  sun  and  the  moon  are  in  quadra- 
ture, there  are  four  tide-ivaves  a  day,  those 
caused  by  the  sun  being  but  slightly  notice- 
able. 

Each  tide-wave  travels  around  the  Earth  in 
-about  tiventy-eight  days. 

While  these  waves  keep  pace  with  the  moon 
•in  its  revolution,  the  Earth  turning  once  a 
day  on  its  axis,  overtakes  a  tide-wave  about 
-every  twelve  hours. 


TJie  tides  of  inland  seas  are  generally  small 
or  else  imperceptible.  Those  of  the  Red  Sea  are 
the  highest. 

High  water  occurs  fifty  minutes  later  on 
each  succeeding  day,  because  the  Earth  re- 
volves in  the  same  direction  that  the  tide-wave 
travels. 

Tlie  continents  greatly  modify  both  the  direc- 
tion and  the.  height  of  the  tide-wave. 

In  the  South  Pacific  ocean,  the  tide-wave 
moves  in  its  normal  direction  towards  the  west9 
or  the  northwest. 

In  the  northern  hemisphere,  the  tide-waves 
are  deflected  towards  the  north. 

On  eastern  coasts  the  height  of  the  tide  is 
usually  from  four  to  six  feet. 

In  j^-shaped  estuaries  which  face  the  tide, 
such  as  the  Bay  of  Fundy,  the  tide  often  reaches 
a  height  of  fifty  feet  or  more. 

The  highest  tides  are  on  the  eastern  and 
southeastern  coasts  of  the  continents. 


1  The  observations  taken  by  Lt.  Greely  in  Kane  Sea  and  Smith  Sound  demonstrate  that  in  those  localities  the  tide- 
comes  from  the  north. 


90 


MONTEITH'S    NEW    P.HYSICALGEOGRAPHY. 


OCEAN    CURRENTS. 


91 


CHAPTER    XV. 

CURRENTS. 

1.  Movements     of     Ocean 
Waters.  —  There  are  other  move- 
ments of  ocean  waters  which  are 
of    great    importance    not    only   to 
mankind,  ^but  also  to  every  form  of 
life  upon  the  Earth.     These  are  cur- 
rents or  rivers  in  the  ocean  itself. 

2.  There    are   currents    in    all 
parts   of  the   ocean,   but  they  are 
more  noticeable  near  the  shores  of 
continents    because    here  their  ve- 
locity is  greatest.     Temporary  cur- 
rents or  movements  of  ocean  waters 
caused  by  winds  are  prevalent  in  all 
parts  of  the  ocean.     These  irregular 
movements   are   not   constant,   and 
therefore,  are    not    classed    among 
ocean  currents. 

3.  The   temperature   of    an 

ocean  current  always  differs  from 
that  of  the  water  surrounding  it, 
and  may  be  either  warmer  or  colder. 

4.  The    color,    too,   of   ocean 
currents  usually  differs  from  that  of 
the  surrounding  water.     Sometimes 
the  contrast  is  so  great  and  the  line 
between    them  so   distinct    that   it 
seems  as  though  a  transparent  par- 
tition separated  them. 

5.  Causes.  —  Various   theories 
have  been  advanced  to  explain  the 
causes  of  ocean  currents,  but  many 
of  the  phenomena  are  as  yet  unac- 
counted for. 

6.  Probably  the  prime  cause  is  the  heat  of  the  sun.  The  temperature  of  the  water  in 
tropical  regions  is  from  80°  to  86°  F.,  while  that  of  the  polar  regions  varies  between  28°  and 
35°  F.  If  water  at  32°,  which  just  fills  a  vessel,  be  heated  to  85°,  it  will  expand  and  a  part 
of  the  water  will  run  over.1 

1  Ocean  water  freezes  at  a  temperature  varying  from  27°  to  32°  F.     The  temperature  depends  on  the  percentage  of  salt. 


In  the  Gulf  Stream. 


92  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


7.  This  is  about  what  occurs  in  the  ocean.    The  water  in  tropical  regions  is  heated,  and, 
increasing  its  bulk,  flows  over  the  surface  toward  the  poles,  while  the  polar  waters  being 
correspondingly  heavier,  flow  below  the  surface  towards  the  equator. 

8.  As  the  colder  "water  Becomes  warm,  it  in  turn  rises  and  flows  toward  the  poles, 
thus  producing  a  circulation  which  never  ceases. 

9.  There  are  many  other  causes  which  are  powerful  aids  to  the  circulation  of  oceanic 
waters.     The  enormous  evaporation  in  the  Torrid  zone  has  a  tendency  to  increase  the  under- 
current of  cold  water  flowing  towards  the  equator. 

10.  The  vast  amount  of  fresh  water  drained  from  the  great  basins  surrounding 
the  Arctic  ocean,  adds  another  cause.    This  water  being  fresh,  is,  bulk  for  bulk,  much  lighter 
than  the  average  ocean  water. 

11.  The  rotation  of  the  Earth  is  likewise  sufficient  to  cause  a  movement  of  ocean 
waters.     Inasmuch  as  the  general  direction  of  the  winds  results  from  the  heat  of  the  sun  and 
the  rotation  of  the  Earth,  it  seems  probable  that  the  circulation  of  ocean  waters  is  governed 
by  the  same  laws.1 

12.  The  unequal  level  of  the  ocean  is  also  an  important  but  comparatively  unknown 
factor  in  the  circulation  of  ocean  waters.     Recent  investigations  show  that  at  the  parallels 
of  28°,  there  is  an  accumulation  of  water  forty  feet  higher  than  the  normal  level  of  the  S'ga 
at  the  poles,  and  about  five  feet  higher  than  the  actual  level  at  the  equator. 

13.  The  winds  have  much  to  do  with  ocean  currents,  and  they  certainly  give  to  them 
their  direction.     Indeed,  there  are  many  distinguished  scholars  who  assert  these  to  be  the 
prime  cause  of  ocean  movements.2 

14.  Classification. — There  are  two  general  classes  of  ocean  currents,  viz. :  warm  cur- 
rents flowing  toward  the  poles,  and  cold  currents  flowing  from  the  polar  regions. 

15.  There  are  also  several  large  areas  within  the  Calms  (see  chart  of  Winds)  which  are 
not  disturbed  either  by  ocean  currents  or  by  winds.     On  account  of  the  immense  quantities 
of  sea-weed  which  have  accumulated  there,  they  are  known  as  Sargasso  seas.3 

16.  Direction  and  Velocity. — Taking  into  account  all  causes  that  form  or  modify 
ocean  currents,  the  general  circulation  of  water  is  :— In  equatorial  regions,  a  steady  flow  of 
water  in  a  westerly  direction.     In  temperate  latitudes,  a  general  movement  of  water  to  the 
eastward. 

17.  In  each  case  the  current  north  of  the  equator  has  a  northerly  drift,  and  south  of 
the  equator,  a  southerly  tendency.     The  average  rate  of  these  great  equatorial  currents  i& 
about  10  miles  per  day.    All  other  currents  are  due  to  these  general  movements,  or  ar& 
closely  connected  with  them. 

18.  The  Gulf  Stream. — One  of  the  most  famous,  and  certainly  the  best  known  ocean 
current,  is  the  Gulf  Stream.     This  current  is  formed  by  the  turning  of  a  portion  of  the  west- 
ward equatorial  current,  along  the  northern  shores  of  South  America. 

1  The  absorption  of  certain  mineral  salts,  such  as  carbonate  of  lime,  by  corals,  mollusks,  and  foraminifera,  to  a  limited 
degree,  affects  the  specific  gravity  and  thus  creates  motion. 

J  The  shores  of  the  continents  also  modify  greatly  the  direction  of  ocean  currents. 

3  These  accumulations  of  sea-weed  have  been  considered  by  many  as  the  result  of  immense  eddies  or  whirlpools,  formed 
tjy  ocean  currents.  Late  researches  do  not  strengthen  this  ineory. 


OCEAN    CURRENTS. 


In  the  Gulf  Stream.    A  Storm  Gathering. 


19.  In  the  Caribbean  Sea, 

it  gradually  turns  northward, 
passing  around  and  between  the 
West  Indies.  A  large  part  of 
this  current  passes  through 
Florida  Strait,  where  it  receives 
a  noticeable  addition  from  the 
heated  waters  of  the  Gulf  of 
Mexico. 

20.  The     two    currents 

combined  have  a  velocity  of 
nearly  five  miles  an  hour  as  they 
pass  through  Florida  Strait ;  but 
to  the  northward,  their  velocity 
gradually  decreases.  Off  Cape 
Hatteras,  it  seldom  exceeds  two 
miles  per  hour.1 

21.  Until  this  current  is  opposite  Charleston,  S.  C.,  its  waters  reach  to  the  bottom  of  the 
sea,  flowing  with  such  force  that,in  many  places, the  bed  of  the  sea  is  swept  bare.3 

22.  In  most  places,  however,  the  bottom  is  strewn  with  minute  shells  brought  from  the 
Caribbean  sea.     These  serve  to  mark  with  accuracy  the  course  of  the  stream. 

23.  By  the  time  this  current  has  reached  latitude  35°-40°,its  waters  have  spread  out  like 
a  fan.     Not  only  does  it  extend  northward  to  the  northwestern  shores  of  Europe,  but  it  also 
reaches  eastward  to  the  strait  of  Gibraltar. 

24.  As  a  surface  current  having  a  definite  direction,  a  measurable  velocity,  and  other 
distinguishing  features,  the  Gulf  Stream  cannot  be  well  traced  north  of  latitude  50°. 3 

25.  The  warm  waters  of  the  Gulf  Stream,  perhaps  combined  with  those  drifted 
from  the  equatorial  current,  are  directly  connected  with  the  mild  climate  of  northwestern 
and  western  Europe. 

26.  Moving  in  northern  latitudes  with  an  almost  imperceptible  motion,  they  give  heat 
to  the  trade-winds,  which,  blowing  over  western  and  northwestern  Europe,  temper  its  cli- 
mate, making  even  the  northern  shores  of  the  Scandinavian  peninsula  far  milder  than  the 
coast  of  Nova  Scotia,  many  degrees  southward.4 


1  The  Gulf  Stream  does  not  flow  around  the  shores  of  the  Gulf  of  Mexico,  as  has  been  until  recently  supposed  ;  its 
direction  in  Florida  Strait  is  to  the  northeast  in  about  the  same  trend  as  the  peninsula  of  Yucatan. 

2  About  fifty  miles  east  of  Charleston,  S.  C.,  and  extending  north  as  far  as  Oape  Fear,  there  is  a  current  setting  strongly 
to  the  southwest,  even  in  the  face  of  a  hard  wind.     This  current  is  much  dreaded  by  pilots  and  masters  of  vessels.     It  is 
thought  to  be  due  to  the  rising  of  the  Arctic  current. 

3  "  The  cold  current  running  along  the  east  coast  of  Greenland  is  both  in  width  and  depth  very  insignificant,  and  rests 
even  near  the  shore,  upon  one  of  warm  water  produced  by  the  Gulf  Stream,     Davis  Sound  and  Baffin  Bay,  on  the  other  hand, 
are  filled  with  cold  or  slightly  warmed  water  to  the  bottom.     Contrary,  however,  to  general  belief,  the  west  coast  of  Greenland 
M  washed  'by  cold  water,  while  a  greatly  heated  current  of  water  coming  from  the  south,  runs  along  the  east  coast  a  distance  of 
40'  to  50'  only  from  the  shore." — BARON  NORDENSKJOLD.    Eeport  of  Greenland  Expedition. 

4  The  port  of  Hamraerfest,  situated  within  the  Arctic  circle,  is  open  to  navigation  throughout  the  year. 


94  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


27.  The  Kuro  Siwo. — The  most  important  current  of  the  Pacific  ocean  is  the  Kuro  Siwo 
or  Japan  current,  a  branch  of  the  equatorial,  flowing  northward  along  the  east  coast  of  Asia. 
This  current  is  not  only  a  much  smaller  one  than  the  Gulf  Stream,  but  it  is  also  a  much 
colder  current.1 

28.  In  winter,  when  the  northeast  monsoons  are  strong,  the  Kuro  Siwo  is  scarcely 
noticeable  farther  north  than  the  southern  limit  of  the  Japan  islands,  and  often  it  is  arrested 
for  days  at  a  time  by  adverse  winds. 

29.  In  summer,  with  the  coming  of  the  southwest  monsoon,  the  Kuro  Siwo  puts  forth 
its  strength  and  passes  the  northern  extremity  of  the  Japan  islands  before  turning  east- 
ward. 

30.  During  all  seasons  of  the  year,  however,  the  Kuro  Siwo  obeys  the  laws  of  ocean  cur- 
rents and  turns  eastward,  where  its  waters,  spreading  out,  are  pushed  towards  the  American 
continent.2 

31.  Cold  Currents. — The  most  important  cold  currents  come  from  the  Arctic  ocean,  one 
through  Baffin  Bay,  and  another  to  the  eastward  of  Greenland.    These  unite  off  the  extremity 
of  Greenland,  and  continue  as  surface  currents,  as  far  south  as  Newfoundland. 

32.  The  cold  current  east  of  Greenland  is,  according  to  Baron  Nordenskjold,  a  surface 
current  flowing  on  the  top  of  a  warm  under  current.     South  of  Newfoundland,  it  becomes  an 
under  current. 

33.  The  Arctic  currents  meet  the  Gulf  Stream  at  the  surface  off  the  coast  of  Labrador. 
The  moisture-laden  atmosphere  is  here  cooled  to  such  an  extent  that  dense  fogs  constantly 
hover  over  this  region. 

34.  The  icebergs  brought  down  by  the  Arctic  current,  on  reaching  the  latitude  where 
these  currents  meet,  drift  helplessly  about  until  they  melt.3 

35.  The  cold  currents  of  the  Antarctic  ocean  consist  of  a  general  drift  of  the  waters 
towards  the  northeast,  rather  than  well-defined  currents. 

36.  Currents  of  the  Indian  Ocean. — The  most  important   current  of  the  Indian 
ocean  is  the  Malabar.    It  is  formed  by  the  northward  bending  of  the  equatorial  current.    The 
Malabar,  like  the  Kuro  Siwo,  is  greatly  modified  by  the  monsoons.4 

37.  Other  Currents. — There  are  several  other  well-defined  ocean  currents,  especially 
in  the  southern  hemisphere,  of  which  the  Brazilian  and  the  Mozambique  are  perhaps  the 
most  important. 

38.  Economy. — Each  of  these  currents,  whether  warm  or  cold,  has  an  important  in- 
fluence upon  that  part  of  the  continent  along  whose  shores  it  flows. 

1  In  latitude  35",  the  average   winter  temperature  of  its   waters  is  63°  F.  ;    the  average   summer  temperature  is 
nearly  70°  F. 

2  No  branch  of  the  Kuro  Siwo  enters  Bering  Sea  ;  on  the  contrary,  the  only  current  of  Bering  Sea  is  a  movement  of 
^ater  southward  through  the  strait. 

8  A  cold  current  has  been  discovered  by  Prof.  Davidson,off  the  coast  of  California,  lying  close  to  the  shore.  Its  origin 
and  destination  are  as  yet  unknown. 

*  There  is  a  surface  current  entering,  and  an  undercurrent  flowing  out  of  the  Red  Sea  through  the  strait  of  Bab  el 
Mandeb.  This  is  said  to  be  owing  to  the  great  evaporation  going  on  in  this  body  of  water.  The  evaporation  from  the 
biiriace  is  sufficient  to  cause  an  inflow  of  water,  while  the  increased  specific  gravity  of  the  remaining  waters,  containing 
About  one-fourth  more  of  mineral  salts,  would  cause  an  outward  flow  at  the  bottom. 


OCEAN    CURRENTS. 


95 


39.  The  influence  of  the  Gulf  Stream  on  northern  and  western  Europe  presents  a  strong 
contrast  to  that  of  the  Arctic  current  upon  Labrador.     The  latter  is  an  uninhabitable,  frozen 
waste  ;  the  former,  the  center  of  the  most  thickly  populated  part  of  the  world. 

40.  Terrific  storms  follow  the  track  of  all  warm  ocean  currents.     This  is  especially  true 
of  the  region  about  the  China  Sea,  and  that  part  of  the  Atlantic  ocean  which  is  east  and 
southeast  of  the  United  States. 

41.  The   exceedingly  large  rainfall  of  the   southeastern   part   of   the  United   States, 
varying  from  70  to  90  inches  per  year,  is  owing  to  the  moisture-laden  winds  of  the  Gulf 
Stream. 

42.  Thus  we  may  see  that  the  ocean,  which  at  first  may  appear  as  a  great  waste,  is  an 
absolute  necessity  to  all  forms  of  life  upon  the  Earth.     It  is  the  source  of  all  fresh  waters ; 
and  by  carrying  away  the  intolerable  heat  of  the  tropics,  it  tempers  alike  the  cold  and  the 
warm  parts  of  the  Earth. 


WHAT  HAS  BEEH  TAUGHT  IK  CHAPTER  XY. 


Currents  of  water  exist  in  all  parts  of  the 
ocean.  Their  temperature  differs  from  that  of 
the  waters  in  which  they  flow.  TJiese  movements 
are  caused  chiefly  by  the  heat  of  the  sun. 

TJie  water  at  the  Equator  is  heated  to  a  tem- 
perature of  about  8O°  F.,  while  at  the  polar  re- 
gions, the  temperature  is  often  as  low  as  27"  or 
28°  F. 

TJie  heating  of  equatorial  waters  increases 
their  bulk  and  causes  a  current  towards  the 
poles. 

These  movements  are  balanced  by  cold  under- 
currents of  water  flowing  from  polar  regions 
towards  the  Equator. 

The  direction  of  ocean  currents  is  due  chiefly 
to  the  winds,  the  shores  of  continents,  and  the 
rotation  of  the  Earth  on  its  axis. 

The  general  direction  of  warm  ocean  cur- 
Tents  is  westward  in  the  Torrid  zone,  and  east- 
ward in  the  Temperate  zones. 

Within  the  region  of  calms,  there  are  areas 
of  undisturbed  waters  filled  with  seaweed,  which 
are  known  as  Sargasso  seas. 

Tlic  direction  of  cold  currents  is  irregular, 
but  always  towards  the  Equator. 

The  Gulf  Stream,  the  most  important  branch 
of  the  equatorial  current,  has  its  origin  in  the 
Caribbean  sea. 


From  the  coast  of  Florida,  it  takes  a  north- 
easterly course  reaching  to  the  North  sea  and, 
spreading  along  the  shores  of  ^vestern  Europe. 

Its  velocity  along  the  southeastern  coast  of  the 
United  States  varies  between  ttvo  and  one-half 
and  four  and  one-half  miles  per  hour. 

TJie  Kuro  Siwo,  the  most  important  current 
of  the  Pacific  ocean,  is  a  smaller  and  colder  cur- 
rent than  the  Gulf  Stream. 

Its  northern  limits  are  controlled  by  the  t non- 
soon  winds  which  often  wholly  check  it  for  days 
at  a  time. 

Its  waters  are  finally  distributed  along  the 
Pacific  coast  of  NortJi  America,  whose  climate 
this  current  is  thought  to  modify. 

The  principal  current  of  the  Indian  ocean  is 
the  Malabar,  a  branch  of  the  equatorial  cur- 
rent. 

TJie  principal  cold  currents  are  the  Arctic 
currents,  one  flowing  southward  through  Baffin 
Bay,  the  other  flowing  to  the  eastward  of  Green- 
land. 

A  feeble  cold  current  flows  out  of  the  Arctic 
ocean  through  Bering  Sea. 

TJie  warm  ocean  currents,  flowing  through 
the  colder  regions  of  the  Temperate  and  Frigid 
zones,  modify  their  climate  by  warming  the 
winds  which  blow  over  them. 


96 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


CHAPTER 


I. 


THE    ATMOSPHERE    A.ND    ITS    MOVEMENTS. 

1.  Density.  —  The  atmosphere,  or  air,  is  the  outer  part  of  the  Earth  which  surrounds 
the  solid  crust.      It  is  extremely  light  ;  one  cubic  foot  weighing  about  one  and  one  fifth 
ounces,  while  a  cubic  foot  of  water  weighs  62.42  Ibs.,  or  about  800  times  as  much. 

2.  Height.  —  The  height  to  which  the  atmosphere  extends  above  the  surface  of  the 
Earth  is  estimated  at  from  50  to  200  miles'.    The  weight  of  a  column  of  air  as  measured  by 
the  barometer  indicates  the  former  height. 

3.  The  great  height  at  which  meteors  are  vaporized,  together  with  the  measured  height 
of  the  Aurora  Borealis  —  both  of  which  are  thought  to  depend  upon  the  atmosphere  —  leads 
to  the  belief  that  it  extends  at  least  200  miles  beyond  the  Earth's  surface. 

4.  Composition.  —  Air  is  composed  of  a  number  of  gases  in  a  state  of  mixture. 
Every  100  parts  contain  77.95  of  nitrogen,  20.61  of  oxygen,  1.40  of  aqueous  vapor,   and 

0.04  of  carbon  dioxide. 

5.  The  amount   of  "water   varies  greatly,   seldom  being 
the   same   on  two   successive   days.      The  amount   of    carbon 
dioxide  is  likewise  variable,  being  greatest  in  thickly  populated 
localities. 

6.  There  are  also  minute  dust  particles,  the  various  vapors 
and   gases  constantly  rising  from  the  earth,  the  products  of 
combustion,  and  occasionally,  traces  of  meteoric  dust.1 

7.  Physical  Properties.  —  Air  is  highly  elastic,  a  pressure 
of  about  15  Ibs.  per  square  inch  being  sufficient  to  reduce  its 
bulk  one  half.    It  will  also  expand  as  the  pressure  decreases. 

8.  The  Barometer.  —  The  pressure  and  the  weight  of  the 
air  are  found  by  means  of  the  barometer,  which  is  shown  in 
the  accompanying  figure. 

9.  The  tube  which  is  closed  at  one  end  is  filled  with  mercury 
and  inverted,  the  open  end  being  placed  in  a  dish  of  mercury. 
The  mercury  sinks  in  the  tube  until  the  column,  if  the  experi- 
ment be  performed  at  the  sea-level,  is  about  thirty  inches  high. 

10.  The  column  is  held  at  this  height  by  the  pressure 
of   the  air  on  the   surface  of   the  mercury   in   the  dish.      In 

other  words,  the  air  and  the  mercury  exactly  balance  each  other,  and,  therefore,  have 
each  the  same  weight. 


The  Barometer. 


1  The  red  sunsets  of  1883-4  have  been  attributed  to  the  latter  cause.  Certain  it  is  that  microscopic  analyses  of  the 
air  proved  the  presence  of  finely  divided  volcanic  matter  in  great  abundance.  By  Professor  Tyndall,  the  blue  color  of  the 
sky  is  attributed  to  the  presence  of  minute  particles  held  in  the  atmosphere. 


THE    ATMOSPHERE    AND    ITS    MOVEMENTS.  97 

4 

11.  By  weighing  the  column  of  mercury, we  at  once  know  the  weight  of  the  column 
of  air  which  balances  it.     At  the  sea  level,  when  the  column  of  mercury  is  thirty  inches 
high,  the  weight  on  every  square  inch  of  surface  is  14.7  Ibs. 

12.  Changes  of  Barometer. — But  the  column  of  quicksilver  in  the  barometer  tube 
is  constantly  changing  in  height.     Therefore,  we  know  that  the  thickness  and  weight  of  the 
layer  of  air  over  our  heads  are  constantly  changing. 

13.  If  the  mercury  rises  to  a  height  of  30.7  inches,  it  indicates  that  a  wave  of  air 
has  gathered  above  us ;   should  it  fall  to  29.4  inches,  it  follows  that  there  is  a  much  thin- 
ner layer  of  air  overhead. 

14.  Observations  taken  in  different  latitudes  at  the  sea  level  show  that  the  atmosphere 
does  not  surround  the  Earth  in  a  layer  of  equal  thickness,  but  is  distributed,  as  you  may 
see  in  the  diagram  on  page  98. 

15.  Like  the  waters  of  the  ocean,  the  greatest  thickness  of  the  atmosphere  is  in 
latitudes  28°  to  35°.     The  decrease  in  thickness  towards  the  poles,  although  not  great,  is 
nevertheless  perceptible. 

16.  The  uneven  distribution  of  the  air  is  shown  in  the  accompanying  table,  being 
the  average  of  many  years  observations  at  the  sea-level. 


Christianburg.  .Latitude,    5°  30'  N.  29.92  in. 

St.  Thomas "        19°  "  29.94  " 

Macao "        23"  "  30.03  " 

Teneriffe . .  "       28°  "  30.08  " 


Tripoli Latitude,  38°         N.  30.21  in. 

Florence "       43°  30'   "  29.99  " 

Dantzic "       54°  30'   "  29.92" 

Reikiavik,.  "        64°         "  29.61  " 


17.  Effect  of  Altitude. — It  is  also  evident  that  as  one  ascends  above  the  sea-level  the 
mercury  will  fall,  because  there  is  less  air  to  balance  it.     Careful  observations  show  that 
this  difference  is  about  one-tenth  of  an  inch  for  every  ninety  feet. 

18.  Torricelli's  Experiment. — The  discovery  of  this  principle  was  made  by  Torricelli 
(Tor-e-chel'-ee),  a  pupil  of  Galileo.      The  conclusion  that  the  barometric  column  is  sustained 
by  the  pressure  of  the  air,  was  denied  by  philosophers  of  that  time. 

19.  Pascal's  Proof. — Pascal  (Pas-kahl'},  a  young  French  scholar,  convinced  of  the 
truth  of   Torricelli's  reasoning,  proposed  to  decide  the  matter  in  a  practical  way.      He 
measured  the  height  of  the  mercury  at  the  base  of  a  high  mountain,  which  he  immediately 
afterward  ascended,  again  measuring  the  height  of  the  column. 

20.  The  result  proved  the  truth  of  his  theory :  the  column  of  quicksilver  steadily  fell 
till  he  reached  the  summit  of  the  mountain  ;  and,  as  he  descended,  the  mercury  rose  again 
to  its  former  height,  thus  conclusively  proving  Torricelli's  theory.1 

21.  The  weight  or  tension  of  the  atmosphere  may  be  readily  found  by  observing  the 
height  of  the  mercury  in  the  barometer  tube.     This,  we  shall  see,  constantly  changes. 

1  Since  the  time  of  Pascal  and  Torricelli  many  improvements  have  been  made  in  the  form  of  the  barometer,  without, 
however,  deviating  in  the  least  from  the  law  established  by  these  scholars. 

The  following  shows  the  effect  of  altitude  upon  the  barometric  column : — At  the  level  of  the  sea,  the  column  is 
30  inches  ;  at  3.4  miles  above  the  sea,it  is  15  inches  ;  at  6.8  miles,  7.5  inches  ;  at  10.2  miles,  3.75  inches ;  at  13.6  miles,  1.87 
inches ;  and  at  the  height  of  17.0  miles,  .94  inches.  In  other  words,  the  weight  and  density  of  the  air  are  halved  for 
every  3.4  miles  above  the  sea-level.  The  highest  altitude  ever  reached  by  a  balloonist  is  about  7£  miles.  At  this  height 
the  barometer  fell  to  7  inches.  At  the  present  time,  the  barometer  is  one  of  the  most  useful  of  all  instruments  in  measuring 
the  altitude  of  mountains. 


98 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


22.  Movements  of  the  Atmosphere. — Like  the  ocean,  the  air  is  subject  to  great 
disturbances.     There  are  tides,  currents,  and  irregular  movements  of  the  atmosphere  on  a 
scale  grander  even  than  those  of  the  sea. 

23.  Winds. — Movements  of  the  atmosphere  are  called  winds.     They  may  be  constant 
and  regular,  or  they  may  be  irregular.     The  former  comprise  those  which  blow  steadily, 
with  constant  force,  and  in  certain  known  directions,  during  a  fixed  period. 

24.  These  winds  are  usually  confined  to  the  ocean  and  sea  coasts.     They  are  known 
as  trade  winds,  passage  winds,  polar  winds,  monsoons,  etc. 

25.  Cause  of  Winds. — The  heat  of  the  sun,  the  prime  cause  of  ocean  movements,  also 
causes  those  of  the  atmosphere,  and  the  laws  which  govern  one  likewise  control  the  other. 

26.  The  general  movements  of  the  air,  like  those  of  the  ocean,  originate  in  the 
equatorial  regions.     Wherever  the  sun's  rays  fall  vertically  on  the  earth,  the  air  becomes 
heated,  and  therefore,  expanded. 

27.  The  heated  air,  being  bulk  for  bulk  lighter  than  cold  air,  rises  ;  at  the  same  time, 
cold  air  is  pushed  in  to  fill  the  vacant  space. 

28.  This  may  be  easily  illustrated  by  throw- 
ing bits  of  tissue  paper  upon  a  hot  stove. 
They  are  at  once  carried  upward  by  the  rising 
current  of  air.  To  fill  the  place  of  this,  cold 
air  is  forced  in  on  all  sides. 


29.  Direction  of  Winds. — If  now  we  ap- 
ply the  same  reasoning  to  the  atmosphere  of 
the  Earth,  we  shall  find  that   the  general 
movements  are  similar. 

30.  These  are  chiefly — An  upward  current  in 
equatorial  regions,  which  sets  toward  thepoles.^ 

Currents  of  air  towards  the  equator  to  re- 
place that  which  has  risen. 

Polar  currents  blowing  toward  the  equator. 

31.  These  laws  are  greatly  modified,not  only 
by  the  spinning  of  the  Earth  on  its  axis,  but 
also  by  the  continental  land  masses. 

32.  Effect  of  the  Earth's  Rotation.— The 

rapid  motion  of  the  Earth  on  its  axis  from 
west  to  east  modifies  the  direction  of  the 
winds  blowing  toward  the  equator,  so  that  north  of  the  equator,  they  blow  towards  the  south- 
west, and  south  of  the  equator,  towards  the  northwest. 

33.  Trade  Winds. — These  winds,  on  account  of  their  favorable  direction  to  vessels 
plying  on  certain  commercial  routes,  have  been  named  trade  winds.     They  are  constant 
throughout  the  year,  blowing  not  only  with  regularity  but  also  with  a  uniform  velocity. 

34.  The  belt  or  zone  of   trade-winds,   moves  a  few  degrees  northward,  during  the 
summer  of  the  northern  hemisphere  and  southward,  during  the  winter.      Their  northern 
limit  in  summer  is  about  latitude  24°  N. ;  in  winter,  about  latitude  5°  N.2 


The  Circulation  of  the  Atmosphere. 


The  upward  current  is  in  the  latitude  where  the  sun's  rays  are  vertical.  2  Reports  of  U.  S.  Hydrographic  Office. 


THE    ATMOSPHERE    AND    ITS    MOVEMENTS. 


99 


Periodical  TTindi  (Montoont)      [ 1 

junction  ofj^riodieal  Wmdt 
Sun  in  2T.  Inclination 
Sun  in  &  Declination 
Calmt  onJand  C.— Variable  "Wtndt  ~V. 


120     ionuitude       160    West      from    160      Greenwich      120  100 


Wind  Chart. — Heavy  arrows  show  direction  of  ocean  currents. 

35.  Variables  and  Passage  Winds. — By  the  time  the  warm,  upward  currents  of  air 
from  the  equator  have  reached   temperate   latitudes,  they  have  become  cold  and  sink  to 
the  surface.     Here,  on  account  of  the  Earth's  rotation,  they  have  a  northeasterly  direction 
in  the  north  temperate,  and  a  southeasterly  direction  in  the  south  temperate  zone. 

36.  These  winds,  often  called  passage-winds,  are  neither  so  regular  nor  so  constant  as 
are  trade  winds.      In  fact,  they  often  blow  in  an  opposite  direction,  and  in  consequence, 
are  often  called  variables,1 

37.  Polar  Winds. — The  polar  winds  also  have  a  slight  westerly  movement,  owing  to 
the  Earth's  rotation.     These  winds  are  tolerably  constant  and,  of  course,  blow  towards  the 
equator.     They  are  met  with  in  latitudes  as  low  as  70°. 

38.  General  Law  of  Winds. — By  looking  at  the  chart  on  page  90, you  will  notice  that 
there  is  a  striking  similarity  in  the  motion  and  direction  of  the  atmosphere  and  those  of  the 
water.     These  may  be  summed  up  as  a  general  westward  motion  in  the  equatorial  regions, 
and  a  general  eastward  motion  in  temperate  latitudes. 

39.  It  is  in  the  ocean  only  that  these  laws  may  be  best  observed.     On  the  land  and 
near  the  coasts,  they  do  not  always  hold  true. 

1  It  will  be  seen  by  consulting  Prof.  Ferrel's  chart,  that  in  the  temperate  zones  there  are  currents  blowing  in  nearly 
opposite  directions,  one  above  the  other.  Sometimes,the  upper  current  prevails,  or  rather  sinks  to  the  surface  of  the  Earth. 
Whenever  this  occurs,the  winds  of  the  north  temperate  zone  have  a  southwesterly  direction  near  the  tropics,  and  a  south- 
easterly  direction  in  the  northern  part  of  the  zone. 


100 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


40.  Monsoons. — Near  all  southern  and  western  coasts,  there  are  winds  blowing  in  a 
certain  direction  for  six  months,  and  then  for  six  months  in  an  opposite  direction.  These 
winds  are  the  monsoons. 


41.  The  best  example  of  such  winds  occurs  in  the  Indian  ocean, 
blow  from  the  northeast  in  winter,  and  from  the  southwest  in  summer. 


The  monsoons 


42.  The  northeast  winds,  blowing  over  land,  are  dry,  and  quickly  parch  the  face  of 
the  whole  region  over  which  they  blow. 

43.  The   southwest  monsoons,  however,  coming  from  the  ocean,   are  warm  and 
moist.     They  pour  their  waters  upon  the  parched  country,  which  soon  teems  with  life.1 

44.  Kegion  of  Monsoon  Winds. — The  chief  monsoon  regions  of  the  western  hemi- 
sphere are  in  the  Gulf  of  Mexico  and  along  the  western  coast  of  Mexico.     They  occur  as  far 
north  as  Bering  sea,  where  they  are  even  more  noticeable  than  in  lower  latitudes. 

45.  Zones  of  Calms. — There  are  narrow  belts  in  several  latitudes  where  the  winds 
seldom  blow,  and  where  they  are  even  then  very  irregular.      These  belts  are  the  calms. 

They  are  not  always  in  the  position 
laid  down  on  the  chart,  for  they  move 
north  or  south  a  few  degrees  with 
the  sun. 

46.  The  reason  why  these  calms  exist 
is   not  with    certainty  known.      The 
equatorial  calms  are  usually  attributed 
to  ascending  currents  of  air  in  latitudes 
where  the  sun's  rays  are  vertical.    For 
a  similar  reason,  the  calms  of  Cancel 
and    Capricorn  are  attributed   to  de- 
scending currents  at  the  tropics. 

47.  Vessels  passing   through   these 
calms  drift  helplessly  about  for  weeks, 
or  perhaps  months.      These  belts  are 

called  "horse  latitudes"    and   "doldrums"   by  sailors.     The  equatorial  calm-belt  lies  a 
:ew  degrees  north  of  the  equator  and  never  passes  south  of  it.      (See  Illustration,  p.  80.) 

48.  Irregular  Winds.— On  large  bodies  of  land,  and  especially  at  some  distance  from 
the  sea  coast,  regular  winds,  such  as  the  trades  and  passage-winds  and  the  monsoons,  are 
greatly  modified  ;  and  in  many  localities,  they  are  entirely  unknown. 

49.  This  is  generally  true  of  eastern  coasts  in  temperate,  and  western  coasts  in  equa- 
torial latitudes ;  for  you  will  see,  by  looking  at  the  Chart  of  Winds,  that  here  the  winds 
blow  from  the  land  instead  of  from  the  sea. 

50.  In  such  localities,  and  also  at  a  distance  from  the  sea,  the  winds  are  local  and 
irregular.    They  are  caused  by  the  heat  of  the  Earth,  and  they  are  liable  to  change  their 
direction  or  to  cease  at  any  moment. 


Sea  Breeze. 


1  There  is  no  sufficient  reason  for  regarding  these  monsoons  as  the  changing  of  the  trade-winds.     They  do  not  cor- 
respond with  them  either  in  direction,  force,  or  temperature. 


THE    ATMOSPHERE    AND    ITS 


51.  Land  and  Sea  Breezes.— 

Along  warm  coasts,  there  is  a  wind 
called  the  "  land-and-sea "  breeze  that 
is  tolerably  regular. 

52.  During  the  day,  the  land  re- 
ceiving  more   heat    than    the   water, 
heats  the  air,  which  rises.     The  cooler 
air  immediately  blows  in  from  the  sea 
to  fill  the  place  of  the  rising  current, 
thus  making  the  sea  breeze. 

53.  At  night,  the  land  parts  with 
the  heat  so  readily  that  it  soon  becomes 
cooler  than  the  water.     The  cool  air  is 
heavier  than  the  sea  air,  which  rises, 

and  its  place  is  filled  by  the  colder  air  blowing  from  the  land. 
breeze. 


Land  Breeze. 


This  produces  the  land 


WHAT  HAS  BEEN  TAUGHT  IK  CHAPTER  XYL 


The  atmosphere  extends  above  the  surface 
of  the  Earth  to  a  height  estimated  between 
5O  and  2OO  miles. 

At  the  sea-level,  the  weight  of  air  is  one-eight- 
hundredth  that  of  water. 

Air  is  composed  of  nitrogen,  oxygen,  and 
carbon  dioxide  gases,  together  with  a  varying 
amount  of  the  vapor  of  water. 

Its  weight  or  pressure  on  the  Earth's  surface 
is  determined  by  measuring  the  height  of  a 
column  of  mercury,  which  the  air  balances. 

The  weight  and  pressure  of  the  air  vary,  the 
variations  being  noted  by  the  barometer. 

At  the  level  of  the  sea  the  pressure  of  the  air 
is  nearly  15  Ibs.  per  square  inch,  supporting  a 
column  of  mercury  about  3O  inches  in  height. 

The  falling  of  the  barometer  indicates  a 
decreased,  and  the  rising,  an  increased  height 
of  air  overhead. 

The  weight  of  the  air  decreases  rapidly  as 
the  altitude  increases,  the  barometer  falling 
one-tenth  of  an  inch  for  every  9O  feet  of  ascent. 

The  air,  like  the  waters  of  the  ocean,  is  in 
constant  motion. 

The  constant  tvinds  consist  of  upper  currents 
from  the  equator  towards  the  poles,  balanced 
by  a  counter  movement  of  currents  from  the 
poles  to  the  equator. 


The  regular  and  constant  currents  of  air 
resemble  those  of  the  ocean,  being  produced  by 
the  expansion  of  air  heated  by  the  sun. 

These  movements  are,  by  the  Earth's  rota- 
tion, modified  to  a  northwesterly  direction  south 
of  the  equator,  and  southwesterly  course  north 
of  it,  being  known  as  trade-winds. 

In  the  temperate  zone,  the  general  motion  of 
the  air  is  eastward  ;  northeastward  in  the  north 
temperate,  and  southeastward  in  the  south  tem- 
perate zone. 

On  western  and  southwestern  coasts,  winds 
called  monsoons,  prevail,  blowing  in  a  certain 
direction  for  six  months,  and  in  an  opposite 
direction,  the  remainder  of  the  year. 

Monsoons  are  alternately  wet  and  dry  winds, 
as  they  blow  over  the  sea  or  over  the  land. 

At  the  equator  and  the  tropics  are  zones 
having  no  regular  wind,  called  calm-belts. 

Regular  tvinds,  such  as  the  trades  and  the 
monsoons,  are  not  perceived  inland,  except  at 
great  altitudes. 

TJie  surface  of  the  Earth  becomes  greatly 
heated,  and  the  rising  of  the  hot  air  produces 
local  winds  which  may  blow  in  any  direction. 

Along  the  coasts,  these  local  winds  are  chiefly 
land-and-sea  breezes  which  bloiv  from  the  sea 
in  the  day-time,  and  from  the  land  at  night. 


102 


NEW    PHYSICAL     GEOGRAPHY. 


CHAPTER 


STORMS,     CYCLONES, 


Waterspouts. 


1.  Cause  of  Irregular  Winds. 

— A  falling  barometer  always  indi- 
cates wind  blowing  from  all  directions 
towards  that  locality  where  the  barom- 
eter is  lowest. 

2.  The  reason  for  this  is  not 
difficult  to  understand.  Whenever  the 
barometer  falls,  it  shows  that  a  less 
weight  of  air  is  pressing  upon  the 
mercury  at  that  particular  place,  than 
elsewhere. 

3.  The  lighter  pressure  may 

result  from  rising  currents  of  warm 
air,  or  it  may  be  that  a  great  amount 
of  vapor  is  present.1 

4.  Area  of  Low  Barometer.— 

In  either  case,  air  will  be  forced  in 
from  all  sides  until  the  pressure  is 
again  equal.  More  certainly  does 
wind  follow  if  there  is  a  rain  storm 

within  the  area  of  low  barometer,  because  when  the  vapor  in  the  air  is  changed  to  rain,  a 

great  amount  of  heat  is  set  free. 

5.  The  heat  thus  set  free  warms  the  air,  which  rises  as  a  strong,upward  current.   There- 
upon, the  colder  air  is  pressed  in  with  all  the  greater  force  to  fill  the  vacant  space.2 

6.  Relation  of  Low  Barometer  to  'Rain. — The  falling  barometer  is  generally,  but 
not  always,  followed  by  rain.     This  depends  upon  the  amount  of  moisture  held  by  the  air  in 
the  area  of  low  barometer. 

7.  The  rising  column  of  air  may  have  a  temperature  of  80°  F.,  and  may  therefore 
contain  as  much  as  10£  grains  of  water  per  cubic  foot. 

8.  For  every  183  feet  of  ascent,  it  will  be  cooled  1°  F.     If  it  rise  1830  feet,  its  temper- 
ature will  fall  to  70°,  and  the  air  can  then  hold  but  8  grains  of  water  per  cubic  foot.     There- 
fore, all  the  moisture  in  excess  of  this  will  be  precipitated  in  the  form  of  rain. 

1  The  specific  gravity  of  the  vapor  of  water  is  .61  ;  that  is,  the  vapor  of  water  is  about  three-fifths  as  heavy,  bulk 
for  bulk,  as  air. 

4  To  the  Pupil. — You  will  recollect  that  the  heat  set  free  when  water  changes  from  a  vapor  to  a  liquid,  is  called 
latent  heat  (see  Chap,  ix.,  p.  57).  When  water  is  changed  to  steam, a  great  amount  of  heat  is  absorbed,  and  disappears  or 
becomes  "latent."  But  if  the  steam  is  again  changed  to  water, all  of  this  heat  is  set  free.  The  heat  thus  set  free,  when  one 
pound  of  steam  is  changed  to  water,  is  sufficient  to  heat  5.37  pounds  of  water  from  the  freezing  to  the  boiling  point,  or  967 
pounds  of  water  lc  F. 


STORMS,     CYCLONES,     AND     TORNADOES. 


103 


Formation  of  Whirlwinds. 


9.  Desert  Whirls.  —  No  one  who  has 
traveled  through  dry,  sandy  plains  has  failed 
to  notice  the  whirlwinds  that  occur  so  fre- 
quently in  those  regions. 

10.  These  whirls  are  most  frequent 

in  the  morning  when  the  air  is  at  rest,  and 
never  when  a  breeze  is  blowing.  The  sun's 
heat  and  the  absence  of  wind  satisfy  all  the 
conditions  necessary  to  produce  whirls  of 
this  kind.1 

11.  The  lower  layer  of  air  has  been 
warmed  by  the  hot  Earth  until  it  has  a  tem- 
perature of  perhaps  90°  F.     The  upper  layer 

at  a  distance  of  3,000  feet  or  more  is  scarcely  75°  F.,  being  1°  cooler  for  every  183  feet. 

12.  This  position  of  the  two  layers  of  air  is  a  very  unstable  one,  because  the  air  next 
the  Earth  is  much  lighter  than  that  above  it. 

13.  By  and  by,  some  slight  disturbance  starts  a  slender  column  of  air  upward.     Imme- 
diately,the  pressure  of  cold  air  forces  the  warm  air  upward  through  the  opening. 

14.  The  warmer  air,   pressed  towards  the  channel  up  which  it  passes,  moves  with 
enough  force  to  carry  a  cloud  of  dust  and  fine  sand.     This  is  carried  upward  until  it  ascends 
hundreds  of  feet  into  the  air. 

15.  As  the  air  from  the  surface  blows  from  all  directions  towards  the  rising  column,  the 
latter  soon  begins  a  whirling  motion.     The  upward  rush,  as  well  as  the  whirl,  increases  in 
velocity, until  the  warm  air  has  ascended,  and  the  colder  layer  has  sunk  to  the  ground. 

16.  On  deserts  and  arid  plains, these  whirls  begin  as  soon  as  the  sun  is  two  or  three  hours 
above  the  horizon.      Sometimes,  several  of  them  may  be  seen  rising  as   slender  columns, 
each  several  hundred  feet  in  height.     During  the  morning,  a  gentle  wind  sets  in,  which, 
by  mixing  the  warm  with  the  cold  air,  prevents  their  further  formation. 

17.  The  whirlwinds  of  the  desert  differ  from  the  cyclones  of  the  Indian  ocean, 
the  hurricanes  of  the  West  Indies,  and  the  typhoons  of  the  China  Sea,  in  violence  only. 

18.  Waterspouts. — Waterspouts  are  caused  in  the  same  manner  as  the  desert  whirls. 
The  whirl  that  makes  a  waterspout  must  have  sufficient  velocity  to  form  a  vacuum  at  its 
center.     Into  this  center  the  water  is  drawn — or  rather  forced.     It  rises  a  few  feet  as  a  solid 
column,  and  then  breaks  into  a  dense  cloud  of  spray  and  vapor. 

19.  Effects  of  Heat  and  the  Earth's  Rotation. — In  these  storms  are  two  elements 
which  make  them  terribly  destructive,  viz.,  the  heat  set  free  by  the  condensation  of  the 
vapor  in  the  air,  and  the  rotation  of  the  Earth  on  its  axis.     The  former  causes  the  storm 
to  move  in  certain  known  directions,  while  the  latter  gives  to  it  its  great  violence. 

20.  Cyclones.— In  the  chart  at  the  top  of  the  next  page,  is  shown  the  usual  path  of 
these  whirling  storms  upon  the  ocean.     They  vary  from  200  to  500  miles  in  diameter,  and 
they  often  travel  2,000  or  3,000  miles  before  their  fury  is  spent. 


1  The  whirlwinds  here  mentioned  are  not  like  those  formed  at  street  corners  where  opposing  currents  of  air  meet. 


104 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


160  Longitude  West  120  from  Greenwich  80 


20  longltaaelEait  60 


Chart  Showing  the  "Region  of  Cyclones. 

21.  The    storm   does    not    cease,  until  it  has  extended  into  temperate  latitudes. 
Here  £he  atmosphere  does  not  contain  so  much  moisture — for  it  must  be  borne  in  mind  that 
the  heat  set  free  by  the  condensation  of  moisture  is  the  fuel  of  cyclones — and  the  storm  finally 
ceases. 

22.  Notice  that  these  storms  have  the  same  direction  as  the  regular  winds — westward  in 
equatorial  regions  and  eastward  in  temperate  latitudes.     They  always  originate  in  the  equa- 
torial   calm-belt    or  doldrums,  but  they  never  occur  within  eight  or  ten  degrees   of  the 
equator. 

23.  Like  the  desert  whirls,  the  beginning  of  the  cyclone  is  a  dead  calm,  for  it  is  such  a 
condition  only  that  will  permit  the  lower  layer  of  air  to  become  heated. 

24.  The  "whirl  is  from  right  to  left  in  the  northern  and  from  left  to  right  in  the  south- 
ern hemisphere.     The  velocity  of  the  wind  in  its  whirling  motion,  varies  from  50  to  125  miles 
per  hour.     The  storm  moves  at  a  rate  varying  from  10  to  50  miles  per  hour.1 

1  The  first  warning  of  the  cyclone  is  indicated  by  the  barometer.  The  dead  calm  which  has  prevailed  for  some  days, 
perhaps,  is  really  a  part  of  the  storm ;  for  it  was  during  this  calm  that  the  conditions  necessary  for  a  cyclone  were  provided. 

There  may  not  be  a  cloud  in  sight  nor  a  breath  of  air  stirring.  The  barometer  begins  to  show  a  slight  unsteadiness, 
and  possibly  a  streamer  or  two  of  cat-tail  clouds,  pointing  towards  the  zenith,  may  be  seen  in  the  south  or  southeast. 
Soon  the  barometer  begins  to  fall,  slowly  at  first,  and  then  more  rapidly.  Fitful  puffs  of  wind  come  from  the  north.  The 
sliy  grows  purple,  and  the  sea  begins  to  heave  in  turbulent  chop-waves.  There  can  now  be  no  longer  any  doubt  about  the 
approach  of  a  storm.  Long  before  this, the  prudent  mariner  has  made  everything  in  the  rigging  and  on  deck  snug  and  close, 
ready  for  the  coming  gale. 

Not  many  minutes  will  elapse  before  the  wind,  at  first  guscy  and  squally,  bursts  into  a  gale,  and  veers  to  the  north- 


STORMS,     CYCLONES,     AND     TORNADOES. 


105 


25.  As  the  laws 
concerning    the 
direction  and  the 
paths    of     these 
storms   are   now 
well  known,  the 
master    may    in 
most  cases  head 
his  vessel,  so  as 
to  sail  out  of  the 
storm. 

26.  To  aid  him 
in    this,    storm 
cards  are  gener- 
ally used.     This 
card,    placed    on 
the  sailing  chart 
in  the  latitude  of 
the    vessel,    will 
at  once  show  the 
relative   position 


Northern  Hemisphere. 


The  Direction  of  Cyclones. 

of  vessel,   storm,   and    the  path    in  which  the  latter 
travels.1 

27.  Looking  in  the  direction  from  which  the  wind 
blows,  the  center  of  the  cyclone  is  on  the  right  hand  in  the 
Northern  and  on  the  left  in  the  Southern  Hemisphere. 

28.  You  will  notice  upon  the  storm  chart  that  the 
regions  in  which  these  cyclones  most  frequently  occur 
are  the  track  of  the  Gulf  Stream,  the  track  of  the  Kuro 
Siwo,  the  region  of  the  Malabar  current,  and  the  eastern 
coast  of  Australia. 

29.  In  the. first  two,  the  storm  track  is  quite  uni- 
form ;  in  all  of  them, the  cyclones  are  very  destructive.2 


Southern  Hemisphere. 


east.  In  a  moment  the  storm  in  all  its  fury  is  upon  tlie  vessel.  If,  by  error,  the  master  has  not  altered  his  course  to  the 
southward,  he  has  but  a  slim  chance  of  riding  out  of  the  storm  •with  a  whole  vessal. 

The  wind  now  increases  to  a  hurricane  and  the  vessel  pitches  about  at  the  mercy  of  the  terrific  chop  seas,  uncon- 
trolled by  helm  or  storm  sheet.  The  roaring  of  the  wind  rises  to  a  deafening  pitch  and  comes  in  gusts  which  throw  the  ship 
on  her  beam  ends.  Canvas  is  blown  into  shreds,  spars  are  torn  off,  and  the  masts  are  splintered. 

In  almost  a  twinkling  the  wind  ceases.  The  vessel  is  now  in  the  center  of  the  cyclone,  or  as  sailors  say,  "in  the 
eye  of  the  storm."  The  sky  is  shrouded  in  murky  blackness  ;  rain  falls  in  torrents  ;  and  no  sound  can  be  heard  but  the  low 
roar  of  the  retreating  storm.  But  a  short  interval — scarcely  half  an  hour — passes,  before  the  opposite  side  of  the  storm 
swoops  upon  the  vessel.  Now  the  wind  is  from  the  southwest,  its  fury  is  not  abated,  and  it  soon  finishes  its  work,  leaving 
the  ship  helpless  and  water-logged, — a  wreck. 

1  For  instance,  the  vessel  is  in  latitude  30°  north,  when  the  premonitory  sign  of  the  storm,  accompanied  by  a  north 
wind,  appears.  In  this  latitude,the  storm  will  move  towards  the  northeast.  By  placing  the  storm  cards  in  the  position  of 
the  vessel,  the  master  at  once  sees  that  to  escape  the  cyclone  he  must  head  his  vessel  south  by  a  point  or  two  west. 

-  The  shores  of  the  bay  of  Bengal  frequently  face  the  cyclones  of  the  Indian  ocean.  The  inblowing  winds,  combined 
with  a  possible  high  tide,  pile  up  the  water  until  it  is  poured  over  the  levees  and  inundates  thousands  of  square  miles. 
Within  200  years,  more  than  half  a  million  people  of  India  have  perished  from  this  cause  alone. 


106 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Ship  Overtaken  by  a  Cyclone. 


30.  Tornadoes.  —  The  tornadoes 
that  sweep  the  Mississippi  valley  do 
not  differ  materially  from  the  cyclones 
of  the  ocean,  except  in  size. 

31.  The  whirl  of  these  tornadoes 
seldom  exceeds  half  a  mile  in  width, 
while  the  center  of  the  storm  is  never 
more  than  a  few  rods  wide.     In  vio- 
lence, however,  they  equal,  if  they  do 
not  surpass,  the  ocean  cyclones. 

32.  Like  all  other  whirls,  the  tor- 
nado is  preceded  by  calm,  sultry  weath- 
er and  a  low  barometer.     It  is  almost 
always  attended  by  a  fall  of  hail  and 
rain,  which  occurs  chiefly  on  the  outer 
edge  of  the  storm. 

33.  Tornadoes  occur,  as  one  might 
suppose,  with  greatest  frequency  in  the 
summer  months.     Their  direction  ac- 
cords with  the  law  of  storms,  and  is 

therefore  towards  the  east  or  northeast  in  temperate  latitudes. 

34.  In  the  United  States,  tornadoes  are  confined  chiefly  to  the  Mississippi  valley, — 
Kansas,  Missouri,  Iowa,  and  Illinois  being  most  often  visited. 

35.  At  the  distance  of  a  few  miles,  the  tornado  appears  as  a  black  funnel  hanging  from 
rapidly  whirling  clouds.    The 

funnel  sways  from  side  to 
side,  often  descending  to  the 
ground  and  dragging  upon  it. 

36.  This   funnel    is    the 
center  of  the  storm,  and  so 
rapid  is  the  whirl,  that  it  is 
almost  a  vacuum.   Whenever 
it  strikes  a  building,  the  latter 
flies  to  pieces  with  almost  ex- 
plosive violence.1 

1  It  is  a  noticeable  fact  that  build- 
ings burst  to  pieces  outwardly.  In  the 
center  of  the  storm  the  atmospheric 
pressure  is  almost  nothing,  while  within 
the  walls  of  the  house  the  outward  pres- 
sure is  fourteen  or  fifteen  pounds  on 
every  square  inch. 

The  destructive  effects  of  torna- 
does are  almost  beyond  belief.  "  Heavy 
carts  are  carried  through  the  air." 
"  Wagon  tires  are  broken  and  twisted."  "  Nails  have  been  driven  head  first  into  solid  planks."  "  Trees  are  twisted  out  of  the 
ground."  "  Large  pieces  of  tin  piping,  guttering,  and  weather-boarding  were  found  six  miles  northeast  of  the  house." 
"Twisted  stovepipe,  lightning  rods,  and  farming  implements  were  found  four  miles  away."  At  Irving,  Kansas,  "large oaks, 
three  feet  in  diameter, were  broken  off  like  pipe-ptems,  and  tough  elms, nearly  as  thick  were  twisted  into  ropes.''  "  These 


Funnel  Cloi 


Tornado. 


STORMS,     CYCLONES,     AND     TORNADOES. 


107 


37.  Within  the  funnel,  one  may 
see  objects  carried  upward  with  a 
whirling  motion. 

38.  Since  the  settlement  of  the 
Mississippi  valley,  over  600  torna- 
does have  been  recorded.     In  40  of 
these, more  than  1,000  persons  have 
been  killed  or  injured. 

39.  Ordinary  Storms. — Near- 
ly all  storms  have  the  nature  of  cy- 
clones, lacking  their  violence,  but 
having  a  much  greater  area. 

40.  Since  the  establishment  of 
the  United  States  Weather  Bureau, 
these  storms  have  been  watched 
with  great  care.     Observations  are 
made  by  trained  assistants  at  the 
same  instant,  three  times  a  day,  in 
about  three  hundred  localities  scat- 
'tered  over  the  United  States.     The 


Barnard  (Missouri)  Tornado.— The  arrows  show  the  direction  in  which 
fence-rails  were  thrown. 


Irving  (Kansas)  Tornado. 

results  are  at  once  telegraphed  to  Wasn- 
ington. 

41.  By  means  of   these  observations, 
the  direction  and  motion  of  the  storm  are 
mapped  out  with  great  precision.    Knowing 
the  velocity  and  direction  of  a  storm,  it  is 
not  difficult  to  predict  its  entire  course. 

42.  From  observations  covering  a  period 
of  fourteen  years,  it  is  found  that  the  ordi- 
nary storm  consists  of  a  center  called  the 
area   of  low  barometer,   towards  which  a 
gentle  wind  blows  from  all  quarters. 

frame  houses  stood  about  in  the  center  of  the  storm  and 
were  completely  destroyed.  .  .  .  The  father,  mother,  and 
grandmother  were  carried  about  200  yards  to  the  east  and 
were  found  lying  within  a  few  feet  of  each  other,  dead.  "  A 
cow  belonging  to  Mr.  Martin  was  carried  a  distance  of  140 
rods,  over  the  tops  of  trees,  and  set  down  uninjured  in  the 
mud."  "  Poultry  are  sometimes  stripped  of  their  featbws, 
although  not  always  killed." — From,  the  Report  of  U.  8. 
Signal  Corps. 


108 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


43.  The  storms  occurring  in  the  central  part  of  the  United  States  originate  in  the  Rocky 
mountains  or  the  Pacific  ocean,  and  travel  eastward.     Those  of  the  Atlantic  coast  usually 
start  in  the  Gulf  of  Mexico  or  the  Caribbean  sea,  and  follow  the  path  of  the  regular  cyclones. 

44.  The  maps  on  page  112,  taken  from  the  records  of  the  Weather  Bureau,  show  the 
origin  and  the  paths  of  these  storms.     In  width,  they  vary  from  a  few  hundred  to  over  a 
thousand  miles.    A  storm  which  starts  in  the  Eocky  mountains  sometimes  travels  half  way 
around  the  Earth. 

45.  The  storms  of  the  Pacific  coast  often  travel  southeastward  towards  and  along  the 
Mexican  coast. 


WHAT  HAS  BSEH  TAUGHT  IN  CHAPTER  XYIL 


The  rapid  falling  of  the  barometer  is  always 
followed  by  wind  which  blows  towards  that  point 
where  the  barometer  is  lowest. 

Itnin  frequently  follows  a  falling  barometer, 
in  wh  ich  case  the  wind  is  apt  to  be  stronger  and 
of  longer  duration,  on  account  of  the  latent  heat 
set  free. 

The  whirls  often  seen  in  deserts  are  caused 
by  the  air  at  the  surface  becoming  heated,  rest- 
ing at  the  same  time  beneath  the  colder  and 
heavier  air  above. 

Finally,  a  passageway  is  opened  through 
which  the  warm,  air  is  forced  upward,  while  the 
cold  air  presses  down  to  the  surface  of  the  Earth. 

The  air  pushed  from  every  direction  towards 
this  channel  acquires  a  whirling  motion  as  it 
passes  upward. 

The  air  becomes  cooler,  at  the  rate  of  1°  for 
every  183  feet  of  ascent. 

Waterspouts  at  sea  are  caused  in  much  the 
same  manner  as  the  desert  whirls;  but  their 
whirl  is  so  rapid  that  a  vacuum  is  formed  at 
the  center,  into  which  the  water  is  forced. 

The  cyclones  of  the  ocean  do  not  differ  from 
the  desert  whirls  except  in  size  and  in  violence. 

The  latent  heat  set  free  by  the  changing  of 
vapor  to  water,  and  the  rotation  of  the  Earth, 
add  greatly  to  the  destructiveness  of  the  storm  ; 
the  former  prolonging  it  and  adding  to  its  vio- 
lence, and  the  latter  causing  it  to  move  in  cer- 
tain definite  directions. 

TJiese  directions  are  west  in  the  Torrid,  east 
&r  northeast  in  the  North  Temperate,  and  east 
V  southeast  in  the  South  Temperate  zone. 


They  are  from  2OO  to  5OO  miles  in  diameter, 
often  traveling  several  thousand  miles  before 
their  fury  is  spent. 

The  whirl  is  from  right  to  left  in  the  northern, 
and  from  left  to  right  in  the  southern  hemi- 
sphere. 

The  cyclone  is  preceded  by  a  dead  calm,  which 
is  its  true  beginning. 

Cyclones  usually,  if  not  always,  originate  in 
warm,  ocean  currents,  and  never  within  six  or 
eight  degrees  of  the  Equator. 

The  tornadoes  of  the  Great  Central  Plain  are 
land  cyclones,  smaller  in  extent,  but,  perhaps, 
equally  as  violent  as  the  cyclones  of  the  ocean. 

The  funnel  of  the  tornado  is  the  center  of  the 
storm,  and  is  almost,  if  not  quite,  a  vacuum. 

The  velocity  of  the  wind  during  a  tornado  often 
exceeds  1OO  miles  per  hour,  the  tornado  moving 
east  or  northeast. 

Nearly  all  ordinary  storms  are  of  the  nature 
of  cyclones,  lacking,  however,  their  violence. 

They  consist  of  a  center,  called  the  area  of  low 
barometer,  towards  which  the  wind  blows  with 
a  spiral  motion,  from,  every  quarter. 

Most  of  the  great  storms  of  the  United  States 
originate  in  the  Rocky  mountains, or,  per  haps,  in 
the  Pacific  ocean. 

They  travel  eastward  or  northeastward,  and 
frequently  cross  the  Atlantic  ocean,  before  they 
are  spent. 

Many  of  the  severe  storms  of  the  Atlantic  coast 
originate  in  the  Caribbean  sea  or  the  Gulf  of 
Mexico > and  travel  in  a  northeasterly  direction 
alony  the  coast. 


CLIMA  TE. 


109 


CHA.PTER 

C  L  I  M  A.  T  E 


An  Arctic  Scene.     Effect  of  High  Latitude  and  Oblique  Rays. 

1.  Causes  of  Difference  in  Climate. — The  climate  of  a  country  is  its  condition 
with  respect  to  heat  and  moisture. 

2.  Every  country  in  the  world  has  certain  peculiarities  of  temperature,  winds,  and 
rainfall,  which,  together  with  its  general  situation,   render  it  different  from  all  other 
countries. 

3.  These  differences  are  due  to  a  great  number  of  causes,  of  which  the  principal  are 
enumerated  below.      The  first  two  of  these  are  astronomical ;   the  others  are  physical 
modifications  of  climate. 


Latitude. 

Inclination  of  the  Earth's  axis. 
Direction  of  winds. 
Direction  of  ocean  currents. 


Height  above  the  sea  level. 
Distance  from  the  ocean. 
Position  and  distance  of  high  mountain- 
ranges. 


4.  Source  of  Heat. — The  sun  is  the  source  of  all  heat  apparent  upon  the  surface  of 
the  Earth,  no  matter  whether  we  consider  the  scorching  beams  pouring  down  upon  the  arid 
desert,  the  coal  fire  within  the  grate,  or  the  back  log  on  the  hearth. 


110 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Effect  of  Altitude.    Climates  between  the  equator  and  the  north  pole  correspond 
with  those  on  the  sides  of  high  mountains  at  the  equator. 


5.  In  every  case,  the  heat  conies  directly  from  the  sun,  or  else  it  is  heat-producing  fuel 
that  has  been  stored  up  by  the  sun  in  ages  past.1 

6.  Altitude. — Elevation  above  the  sea-level  has  much  to  do  with  the  temperature  of  a 
place.     In    a    previous    chapter,  we 

learned  that  the  air  becomes  cooler 
by  one  degree  in  every  183  feet  of 
ascent  above  the  sea-level.  The  effect 
of  this  is  obvious. 

7.  In  the  Torrid  Zone,  at  an 

elevation  of  from  14,000  to  16,000 
feet,  we  find  the  limit  of  perpetual 
snow ;  while  between  the  snow-line 
and  the  sea-level,  almost  any  medium 
temperature  may  be  found.2 

8.  Many  important  cities  of 

South  America  are  situated  within 
the  torrid  zone.  Quito,  Cuzco,  Potosi, 
and  Pano  have  an  elevation  varying 
from  9,500  to  12,000  feet.  Their  great 
elevation  renders  their  climate  cool 
and  delightful. 

9.  The  city  of  Mexico  has  an 

elevation  of  7,400  feet.  Yera  Cruz,  in  the  same  latitude,  is  at  the  sea-level.  Few  cities 
in  the  world  have  a  climate  so  agreeable  and  healthful  as  that  of  Mexico.  That  of  Vera 
Cruz,  on  the  contrary,  is  very  hot,  and  at  times  pestilential. 

10.  Distance  from  the  Ocean. — Distance  from  the  sea  affects  chiefly  those  localities 
over  which  the  trade  or  other  sea-winds  blow.    As  the  distance  from  the  sea  increases,  the 
daily  variations  in  temperature  are  likewise  greater.    The  amount  of  moisture  contained 
in  the  air  and  also  the  amount  of  rainfall  usually  decrease. 

11.  In  the  vicinity  of  sea- coasts,  climate  is  greatly  tempered  by  the  rapid  evap- 
oration of  ocean  waters,  whereby  an  enormous  amount  of  heat  is  transferred  from  warmer 
to  colder  regions. 

12.  You  will  recollect  that  when  water  is  changed  to  vapor  (see  p.  57)  a  great  amount 
of  heat  is  absorbed.      If  the  vapor  with  its  stored-up  heat  be  now  carried  by  winds  to 
colder  localities,  and  again  changed  to  water,  all  this  heat  is  again  set  free.3 

1  In  its  ordinary  sense,  combustion  or  burning  means  a  chemical  combination  of  carbon  with  oxygen.  When  the 
carbon  of  the  coal  or  the  wood  unites  with  the  oxygen  of  the  air, very  great  heat  is  evolved,  and  carbon  dioxide,  commonly 
called  carbonic  acid  gas,  is  formed.  Sunlight  and  heat  have  the  power  of  separating  these  elements  which  have  formed 
the  carbon  dioxide.  The  green  leaves  and  blades  of  grass  are  nature's  laboratory  wherein  this  work  is  done.  The  carbon  is 
restored  to  the  plant,  while  the  oxygen  is  given  to  the  air. 

8  The  limit  of  perpetual  snow  varies  with  latitude.  In  Patagonia,  it  is  about  3,000  feet ;  in  Chili,  8,600  feet ;  iu 
Bolivia,  16,000  feet ;  in  the  western  slope  of  the  Sierra  Nevada  mountains,  10,000  feet ;  and  at  cape  North,  2,400  feet 

8  More  than  100,000  cubic  miles  of  water  are  each  year  taken  up,  in  the  form  of  vapor,  from  the  ocean,  and  again 
deposited  as  rain  or  as  snow.  If  one-fourth  of  this  amount  be  carried  to  temperate  and  to  polar  latitudes,  the  heat  thus 
transferred  would  be  sufficient  to  raise  nearly  130,000  cubic  miles  of  water  from  the  freezing  to  the  boiling  point.  "We 
can  scarcely  form  a  too  greatly  exaggerated  estimate  of  the  tempering  of  climate  by  rain-bearing  winds." 


CLIMA  TE. 


Ill 


13.  Hence  we  learn  that  all  moisture-laden  winds  are  warm,  if  only  the  vapor  they 
contain  be  condensed  and  the  heat  thereby  set  free. 

14.  Consulting:  the  wind  chart  on  page  99,  you  will  find  that  the  moisture-bearing 
winds  of  the  temperate  zone  are  the  ocean  winds  blowing  from  the  west.     The  effect  of 
these  winds  upon  the  climate  is  marked — all  ivestern  coasts  in  the  temperate  zones  are  much 
warmer  than  eastern  coasts  in  the  same  latitudes. 

15.  Ocean   Currents.  —  The  presence  of  warm  ocean  currents  has  likewise  a  mod- 
erating effect  upon  climate.      The  warmth   derived   from 

them,  combined  with  the  latent  heat  transferred  by  evap- 
oration, make  them  the  most  powerful  of  all  physical 
agencies  in  tempering  climate. 

16.  The  British  Islands,  lying  in  the  same  latitude 
as  Labrador,  are  seldom  covered  with  snow  for  more  than 
a  few  days  at  a  time,  and  ice  never  forms  in  their  harbors. 
Labrador,  on  the  contrary,  is  covered  with  ice  and  snow 
during  eight  months  of  the  year,  and,  in  some  places,  its 
coast  is  ice-bound  even  in  midsummer. 

17.  Norway  and  southern  Greenland  lie  between  the 
same  parallels    of    latitude.      The    former   has  a  climate 
hardly  so  cold  as  that  of  Maine.     The  port  of  Hammerfest, 
situated  within    the    frigid    zone,   is   free  from  ice-drifts 
and  open  to  commerce  throughout  the  year. 

18.  Greenland, 
on  the  other  hand,  is 
shrouded    in   a   per- 
petual winter.      Ex- 
cept a  few  portions 
of  land  bordering  its 
southern    coast,    the 
whole     surface     has 
been  for  ages  covered 
with  ice  and  snow. 

19.  These  great 
differences  in  climate 
are  the  work  of  the 
physical    agents   we 
have    considered    in 

the  preceding  paragraphs,  via. :  the  winds,  the  latent  heat  of  water  transferred  by  the  winds, 
and  the  warm  ocean  currents. 

20.  Variations  in  temperature   during  the  year  will,   for  the  foregoing  reasons, 
be  much  greater  on  eastern  than  on  western  coasts  of  the  temperate  zones,  and  they  will 
be  greater  in  the  interior  of  a  continent  than  on  either  of  its  coasts.1 

1  The  following  low  temperatures  have  been  registered  by  the  Signal  Service  Bureau  :  Fort  Buford,  Dakota,  —  40°  ; 
Pembina,  Dak.,  —  48°  ;  Fort  Ellis,  Montana,  —  53°  ;  Fort  Brady,  Mich.,  —  55°.  Lt.  Schwatka,  the  Arctic  explorer,  recorded 
a  temperature  of  —  70°  in  King  William's  Land.  It  is  doubtful  if  a  hotter  region  exists  than  the  Colorado  desert  in  south- 
eastern California.  A  temperature  of  135°  ha«  been  registered,  and  it  frequently  exceeds  120°. 


Scene  in  Florida — Effect  of  warmth  and  moisture. 


CLIMA  TE. 


113 


This  is  shown  by  the  following  records  from  the  Weather  Bureau — Report  of  1881 : 


LOCALITY. 

SITUATION. 

AV.   OF  COLDEST 
MONTH. 

AV.   OF  WARMEST 
MONTH. 

GREATEST 
MONTHLY  RANGE. 

TjQS  Aii'^clcs   (Jill 

^^estern  Coast     

49  1° 

69° 

29° 

San   Francisco,  Cal  . 

49.6° 

59.6° 

38° 

.Boston    3T;iss 

32.6° 

69.9° 

69° 

Bismarck,    Da 

—1.2° 

70° 

83° 

21.  Distribution  of  Bain.1 — The  rain  or  snow  falling  on  the  land  in  one  year  would, 
if  evenly  distributed,  form,  a  layer  of  water  exceeding  three  and  one-half  feet  in  thickness. 
The  distribution  of  the  rainfall,  however,  is  by  no  means  even.     Many  parts  of  the  Earth 
are  constantly  deluged  with  rain,  while  others  receive  but  little  or,  perhaps,  none  at  all. 

22.  Periodical  Rains. — There  is  also  a  great  difference  in  the  seasons  during  which 
rain  falls.    In  some  localities,  rain  may  fall  during  any  part  of  the  year;  in  others,  it  falls 
during  the  winter  months  only. 

23.  It  may  be  stated,  as  a  general  law,  that  periodical  rains  occur  along  the  western 
coasts  of  countries  lying  within  the  temperate  zones,  and  in  those  regions  over  which 
monsoons  blow. 

24.  In  the  Torrid  zone,  and  especially  near  the  equator,  rains  fall  almost  incessantly 
during  a  great  part  of  the  year.     Towards  the  tropics,  however,  the  rains  are  more  peri- 
odical in  their  occurrence. 

25.  The  "rain-belt"  does  not  go  south  of  the  equator.     For  this  reason, the  rainfall  is 
more  periodical  south  of  the  equator  than  north  of  it.     In  the  Torrid,  as  in  other  zones,  the 
rain  comes  with  the  sea-wind. 

26.  The  northern  part  of  South  America  is  so  situated  as  to  receive  the  full  force  of 
this  rain-bearing  wind.     In  consequence,  the  whole  region  is  drenched  with  rain  during 
much  of  the  year. 

27.  The  Andes  Mountains  on  the  western  border,  rising  nearly  as  high  as  the  rain- 
clouds  themselves,  condense  most  of  the  remaining  moisture,  so  that  little  or  none  falls  on 
the  western  slope. 

28.  In  the  Temperate  zones,the  conditions  are  very  different.     Here, the  rain-winds, 
which  are  in  part  monsoons,  blow  from  the  west  or  from  the  southwest.    Hence,  the  western 
slopes  are  well  watered,  while  east  of  all  high  mountain -ranges,  the  rainfall  is  very  meagre. 

29.  The  desert  of  Atacama  (ah-tah-kah'mah)  in  South  America  and  the  Great  Basin  of 
the  United  States  are  fine  illustrations  of  this  law.     The  rainfall  of  these  regions  seldom 
exceeds  eight  or  ten  inches ;  while   on   the   opposite  slopes,  it  often  reaches  120  inches 
annually. 

30.  Rainfall  of  the  United  States. — In  the  United  States,  the  amount  of  rainfall 
varies  greatly,  ranging  from  a  few  inches  to  more  than  100  inches  yearly.    By  consulting  the 
Chart  on  p.  113,  it  will  be  seen  that  the  Great  Basin  receives  less  rain  than  any  other  part  of 
the  country.     For  the  past  thirteen  years,  the  rainfall  of  this  region  has  averaged  less  than 
troi  inches  yearly. 


The  rainfall  of  a  country  includes  also  the  number  of  inches  of  melted  snow. 


114 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


31.  The  north-western  and  the  southeastern  coasts  receive  the  greatest  amount 
of  rain.     In  these  localities,  the  annual  fall  varies  from  65  to  100  inches  or  more. 

32.  In  the  Rocky  mountains  and  throughout  the  western  highlands,  the  average 
fall  is  about  fifteen  inches. 

33.  The  Mississippi  valley  and  the  Atlantic  slope  are,  however,  much  more  plenti- 
fully watered,  receiving  from  thirty-five- to  sixty-five  inches  of  rain  yearly.     The  former  is 
about  the  amount  falling  upon  the  "wheat"  states; the  latter, on  the  "cotton"  states. 

34.  On  the  Pacific  slope,  the  rainfall  increases  uniformly  towards  the  north.     In  the 
Mississippi  valley  and  on  the  Atlantic  coast,  the  increase  is  toward  the  southeast.     Little 
or  no  rain  falls  on  the  Pacific  slope  during  the  summer;  and  in  this  region,  thunder  and 
lightning  are  almost  unknown.1 

35.  Astronomical  Causes  of  Climate. — There  are  certain  changes  of  climate  due 
to  the  direction  in  which  the  sun's  rays  strike  the  Earth — whether  vertically  or  obliquely. 
These  changes  are  greatly  increased  by  the  inclination  of  the  Earth's  axis. 

36.  The  Earth's  distance  from  the  sun  is  so  great  that  those  rays  which  reach  the 
Earth  are  practically  parallel ;  but  as  the  surface  of  the  Earth  is  curved,  it  is  evident  from 
the  accompanying  illustration,  that  while  some  rays  strike  the  surface  vertically,  others 
meet  it  obliquely. 

37.  The  rays  both  of  heat  and  light  reaching  the  Earth 
at  B  are  perpendicular.    Those  meeting  the  surface  towards 
A  and  C,  however,  strike  more  and  more  obliquely,  until,  at 
those  points,  they  pass  the  Earth  without  touching  it. 

38.  Whenever  the  sun's  rays  strike  the  Earth's  surface 
vertically,  much  of  the  heat  they  contain  is  absorbed,  being 
used  in  heating  the  Earth  and  the  atmosphere.     The  oblique 
rays,  however,  part  with  much  less  of  their  heat,  which,  like 
the  light  they  bear,  is  reflected  away.2 

39.  Another  reason  why  the  small  amount  of  heat  is  derived  from  the 
oblique  rays  is  the  fact  that  the  heat  is  spread  over  a  much  greater  surface  than 
would  be  the  case  if  the  rays  were  vertical. 

40.  This  may  be  seen  in  the  following  diagram.     The  sun's  rays  falling 
in  the  surface  A  B  are  vertical.     The  same  amount  of  solar  heat,  however, 
falling  on  C  D,  a  surface  twice  as  large,  is  distributed  over  twice  as  much  space. 

41.  Hence,  we  are  able  to  understand  that  the  climate  of  a  country,  so 
far  as  temperature  is   concerned,  depends   more   upon   latitude  than  on  any 
other  one  cause.     Within  the  Torrid  zone,  where  the  sun's  rays  are  always 
vertical,  or  nearly  so,  a  perpetual  warmth  of  summer  obtains,  while  toward 
the  poles, the  climate  gradually  becomes  one  of  icy  coldness. 


Effect  of  Curvature. 


QY 

Oblique  Rays. 


1  From  late  investigations, it  seems  probable  that  the  rainfall  of  a  country  is  subject  to  changes  which  require  long 
periods  of  time  to  complete. 

*  We  are  less  sensible  to  the  direct  heat  of  the  sun  than  we  are  to  the  heat  radiated  from  the  Earth  and  the  air.  It 
frequently  happens  that  the  sun's  rays  will  scorch  and  blister  the  skin,  while  at  the  same  time  the  weather  seems  uncom- 
fortably chilly.  There  is  no  paradox  about  such  a  condition  of  weather  ;  it  is  cold  because  the  ground  and  the  air  have  not 
been  warmed.  It  is  well  to  bear  in  mind  that  the  heat  which  is  required  to  warm  our  bodies  comes  to  us  second  or  third 
hand — that  is,  from  the  Earth  and  the  air. 


CLIMATE. 


115 


MARCH  21-23 


JUNE  21-23    ., 


Sun's  rays  reach  from  pole  to  pole. 
Spring  in  North  Temperate  zone. 
Autumn  in  South  Temperate  zone. 

SUN. 


SEPT. 


Sun 's  rays  reach  23)4°  beyond  N.  pole. 
Summer  in  North  Temperate  zone. 
Winter  in  South  Temperate  zone. 
Day  in  North  frigid  zone. 
Night  in  South  Frigid  zone. 


Sun 's  rays  reach  23%°  beyond  S.  pole. 
Summer  in  South  Temperate  zone. 
Winter  in  North  Temperate  zone. 
Day  in  South  Frigid  zone. 
Night  in  North  Frigid  zone 


Sun's  rays  reach  from  pole  to  pole. 
Spring  in  South  Temperate  zone. 
Autumn  in  North  Temperate  zone. 
The  Change  of  Seasons. 

42.  Were  the  position  of  the  Earth's  axis  perpendicular  to  the  plane  of  the  orbit 1  there 
would  be  no  changes  in  the  climate  of  any  locality.     Each  place  would  have  a  tolerably 
uniform  temperature  throughout  the  year. 

43.  Change  of  Seasons. — But  on  a  large  portion  of  the  Earth,  there  are  alternations 
of  climate,  which  are  called  "change  of  seasons."    These  changes  are  due  to  the  inclina- 
tion or  tipping  of  the  Earth's  axis. 

44.  The  axis  of  the  Earth  (except  as  indicated  in  note,  p.  9)  preserves  a  direction 
that  does  not  change,  making  an  angle  of  about  23£  degrees  with  the  plane  of  the  Earth's 
orbit,  and  pointing  towards  the  north  star. 

45.  By  studying  the  diagram  above,  you  will  notice  that  in  the  month  of  June  the  Earth's 
axis  is  inclined  so  that  the  sun's  rays  are  vertical  at  the  Tropic  of  Cancer.     They  are  very 
slightly  oblique  in  the  North  Temperate  zone,  while  they  reach  23  £  degrees  beyond  the  north 
pole,  marking  the  position  of  the  Arctic  circle. 

46.  In  this  position  of  the  Earth,  it  is  the  season  of  summer  in  the  North  Temperate 
zone,  and  both  summer  and  day-time  in  the  North  Frigid  zone. 

47.  In  the  southern  hemisphere,  the  sun's  rays  are  oblique,  and  lack  23£  degrees  of  reach- 
ing the  pole.     This  is  the  winter  of  the  South  Temperate  and  night  of  the  South  Frigid  zone. 

48.  By  the  middle  of  September,  three  months  afterward,  the  Earth  has  reached  a 
position  in  her  orbit  where  the  sun's  rays  reach  each  pole.     This  season  is  the  autumn  of 
the  Northern  and  the  spring  of  the  Southern  Hemisphere. 

1  The  meaning  of  "plane  of  the  Earth's  orbit"  may  be  illustrated  by  thrusting  a  knitting  needle  through  an  orange 
o;  a  ball,  and  suspending  it  one-half  submerged  in  a  vessel  of  water.  Incline  the  ball  until  the  knitting-needle  makes  an 
angle  of  23^  degrees  with  a  vertical  line.  The  surface  of  the  water  represents  the  plane  of  the  Earth's  orbit. 


US  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 

49.  By  the  21st  of  December,  the  Earth  has  passed  half-way  round  the  orbit.     Now,  the 
sun's  rays  are  vertical  at  the  Tropic  of  Capricorn,  and  very  oblique  in  the  North  Temperate 
zone. 

50.  It  is  midwinter  in  the  Northern,  and  midsummer  in  the  Southern  Hemisphere.     The 
sun  shines  bright  upon  the  ice-fields  of  the  South  Frigid  zone,  while  the  North  Frigid  zone 
is  shrouded  in  wintry  night. 

51.  Division   of  Seasons. — The  division  of  the  year  into  four  climatic  seasons  is 
noticeable  chiefly  in  the  temperate  zones,  and  there  are  parts  of  these  zones  in  which  the 
changes  of  season  are  not  well  marked. 

52.  Along  western  coasts  of  the  temperate  zones,  there  are  practically  but  two  seasons  ; 
a  rainy  or  winter,  and  a  dry  or  summer  season.     There  are  no  great  variations  of  tem- 
perature. 

53.  In  the  Torrid  zone,  the  only  season  is  that  of  perpetual  summer.     But  while 
there  are  almost  daily  rains  in  parts  of  this  zone,  in  other  portions,  the  rainy  and  the  dry 
seasons  are  distinct. 

54.  In  Frigid  zones,  the  seasons  are  those  of  day  and  night ;  the  former  being  the 
summer,  the  latter  the  winter.     Within  the  Frigid  zones,  the  day  and  the  night  are  said  to 
be  six  months  each  in  duration. 

55.  This  is  true  at  the  poles,  but  not  strictly  true  elsewhere.     At  the  Arctic  circle,  for 
instance,  the  length  of  the  day  varies  from  0,  on  the  21st  of  December,  to  24  hours  on  the 
21st  of  June.     On  this  day,  the  sun  does  not  set,  its  lowest  position  being  on  the  horizon,  or 
perhaps  a  trifle  below  it,  if  there  be  a  land  sky. 

56.  With  each  succeeding  day,  the  sun  apparently  dips  farther  and  farther  below  the 
horizon.     In  March  and  September,  the  sun  is  above  the  horizon  twelve  hours  and  below  it 
twelve  hours.     By  the  21st  of  December,  the  sun  does  not  rise  above  the  horizon.     The  day 
is  now  0  and  the  night  24  hours  long. 

57.  At  the  poles,  the  sun  appears  to  sweep  horizontally  around  the  sky.    Each  day, 
it  moves  a  little  farther  above  the  horizon,  until,  by  the  21st  of  June,  it  is  23£  degrees  high. 
By  the  middle  of  September,  it  is  on  the  horizon^  and  by  the  21st  of  December,  23£  degrees 
below  it. 

58.  If  the  observer  move  a  degree  or  two  from  the  pole,  the  sun  begins  to  show  a  slight 
variation  in  its  distance  above  the  horizon.     This  increases  as  the  observer  goes  southward. 

59.  Isotherms. — Because  the  western  coasts  of  the  temperate  zones  face  the  warm 
and  rain-bearing  winds,  it  is  evident  that  zones  of  equal  temperature  will  not  correspond  to 
the  astronomical  zones  of  the  Earth. 

60.  On  the   contrary,  the  astronomical  zones  of  the  Earth  have  no  significance  so 
far  as  climate  is  concerned,  as  they  indicate  neither  temperature  nor  the  distribution  of 
moisture. 

To  the  Teacher. — It  should  be  thoroughly  understood  by  the  pupil  that  the  Arctic  and  Antarctic  circles  mark 
the  limit  of  the  sun's  rays  beyond  the  pole  in  the  frigid  zones  at  the  21st  or  22d  of  June  and  December  respectively.  At  the 
same  time,  it  may  be  shown  that  the  tropics  of  Cancer  and  Capricorn  mark  the  northern  and  the  southern  limit  of  vertical 
rays  on  those  dates.  A  globe  is  preferable  for  this ;  but  it  is  an  excellent  plan  to  require  each  pupil  to  construct  a  diagram 
similar  to  the  illustration  on  page  115. 


C L  I MA  TE. 


117 


120        LorpituHe       80 We 6V  from      40        Greenwich       0          Lonsritude      40  East 


Isothermal  Lines  and  Zones. 

61.  Each  line  on  the  map  above  is  drawn  through  places  having  a  uniform  average 
temperature.     These  lines  are  called  isothermal  lines,  or  isotherms,  and  the  zones  they 
bound,  isothermal  zones.1 

62.  The  irregularity  of  these  lines  shows  the  influence  of  winds,  high  mountains,  and 
ocean  currents.     The  hot,  cold,  and  temperate  zones  of  the  earth  are  therefore  bounded 
by  isotherms,  and  not  by  parallels  of  latitude. 

63.  In  the  temperate  zones,  the  isotherms  bend  northward  as  they  cross  to  the  western 
coast  of  a  continent.     On  the  ocean,  the  isotherms  are  quite  regular,  changing  their  direction 
but  slightly  ;  but  in  mountainous  regions,  their  curves  are  numerous  and  sharp. 

64.  Effect  of  Forests. — Most  important  factors  in  the  climate  of  a  country  are  its 
forests.     Eemove  the  growing  timber  and  shrubbery,  and  barrenness  soon  follows. 

65.  The  reason  for  this  is  plain.     The  roots  of  plants  not  only  hold  much  of  the  water 
in  the  soil,  but  they  also  hold  the  soil  itself  to  the  slopes  and  hillsides,  thereby  preventing 
its  richest  portions  from  being  carried  away. 

66.  Experience  has  shown  that  many  of  the  disastrous  river  floods  occurring  in  the 
United  States  and  Europe,  are  due  to  the  destruction  of  forests,  more  than  to  any  other  cause. 
The  water  that  the  rootlets  of  plants  would  have  otherwise  retained  in  the  soil  is  poured  into 
river  channels,  which  are  not  large  enough  to  contain  it. 

1  From  Greek  words,  meaning  equal  Tient,  or  temperature. 


118 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


67.  A  still  more  serious  effect  of  the  destruction  of  forests  is  the  gradual  decrease  of 
rainfall.     The  arid  condition  of  Syria,  once  the  most  fertile  region  of  the  world,  is  attributed 
largely  to  the  destruction  of  its  growing  timber. 

68.  On  the  other  hand,  the  planting  of  eucalyptus  forests  along  the  valley  of  the  Nile 
has  appreciably  increased  the  rainfall  during  the  past  fifty  years. 


WHAT  HAS  BEEN  TAUGHT  IK  CHAPTER  XYIIL 


The  climate  of  a  country  is  its  condition  with 
reference  to  heat  and  moisture. 

The  chief  causes  of  difference  in  climate  are 
latitude,  inclination  of  the  Earth's  «a?i.s,  winds, 
ocean  currents,  and  altitude. 

The  sun  is  the  great  source  of  heat ;  the 
transfer  of  heat  is  accomplished  by  winds  and 
ocean  currents. 

Temperature  depends  much  on  latitude,  the 
climate  being  hottest  at  the  equator  and  becom- 
ing colder  totvards  the  poles. 

Temperature  decreases  uniformly  as  the  alti- 
tude increases. 

Variations  in  temperature  are  greater  at  a 
distance  from  the  sea-coast  than  near  it. 

Tlie  warm  winds  of  the  temperate  zones  are 
those  blowing  upon  the  western  coasts. 

Their  heat  is  derived  from  the  latent  heat 
of  the  moisture  they  contain  and  from  the 
warmth  of  the  waters  over  which  they  blow. 

The  mild  temperature  of  the  British  Islands 
and  Norway,  compared  with  the  cold  climate 
of  Labrador  and  Greenland,  is  due  to  warm 
-winds  and  ocean  currents. 

The  rainfall  of  different  countries,  or  even 
that  of  different  parts  of  the  same  country ,  is 
not  uniform  in  amount. 

TJie  greatest  amount  of  rain  falls  in  the 
Torrid  zone,  near  the  equator- 

Periodical  rains  occur  usually  in  western 
and  southwestern  coasts  of  temperate  latitudes. 

In  the  interior,  and  on  eastern  coasts  of  the 
temperate  zones,  rains  may  occur  at  any  time 
of  the  year. 

Tlie  yearly  rainfall  of  the  Great  Central 
Plain  varies  from  35  inches  in  the  north,  to 
65  inches  in  the  south. 


The  rains  of  the  Pacific  coast  of  the  United 
States  are  periodical.  They  vary  from  12  inches 
in  the  south-  *»  lOft  inches  in  the  north,  and 
occur  in,  winter  only. 

TJie  decrease  of  temperature  towards  the 
poles  is  due  to  the  oblique  angle  in  which  the 
sun's  rays  strike  the  Earth. 

Clianges  of  season  are  due  to  the  inclination 
of  the  Earth's  axis  to  the  plane  of  its  orbit. 

On  the  21st  of  June,  the  sun's  rays  are  ver- 
tical on  the  Tropic  of  Cancer  and  oblique  in 
the  South  Tetnperate  zone,  the  seasons  being 
respectively  summer  and  winter. 

On  the  21st  of  December,  the  sun's  rays  are 
vertical  on  the  Tropic  of  Capricorn,  thereby 
reversing  the  seasons  in  the  two  zones. 

In  March  and  September,  the  sun's  rays 
reach  both  poles.  It  is  then  spring  in  the 
Northern,  and  fall  in  the  Southern  Hemi- 
sphere. 

The  seasons  of  polar  regions  are  practically 
day  and  night;  the  former  being  the  summer, 
and  the  latter,  the  winter  season. 

Tfie  climate  of  th^  Torrid  zone  is  that  of 
perpetual  summer,  the  seasons  being  the  wet 
and  the  dry. 

Lines  passing  through  localities  having  the 
same  temperature  are  called  isotherms ;  and 
the  zones  they  bound,  isothermal  zones. 

In  temperate  zones,  isotJierms  bend  north- 
ivard  towards  the  western  coasts  of  continents. 

Forests  and  growing  sJirubbery  preserve  the 
moisture  of  the  soil  by  causing  much  of  the 
rain  to  soak  into  the  ground. 

The  destruction  of  forests  is  frequently  fol- 
lowed by  disastrous  floods  and  a  decrease  of 
moisture  in  the  soil. 


THE    DISTRIBUTION    OF    LIFE. 


119 


CHAPTER 

THE      DISTRIBUTION      OF      I,  I 


Tropical  Vegetation. 

1.  Plants. — Plants  were  among  the  earliest  forms  of  life  to  appear  on  the  Earth,  and 
though  nearly  all  of  the  first  species  are  now  extinct,  they  have  been  replaced,  not  only  by 
similar  species,  but  also  by  higher  ones.     Unlike  most  other  forms  of  life,  plants  take  their 
food  directly  from  the  soil,  the  air,  and  the  water.1 

2.  Composition. — Plants  consist  of  from  three-fourths  to  nine-tenths  water.     Carbon, 
nitrogen,  hydrogen,  oxygen,  potassium,  lime,  phosphorus,  and  silicon,  in  various  forms  and 
proportions, compose  the  remaining  parts.2 

3.  The  skeleton  of  the  plant  is  always  carbon.     Silicon  when  present,  forms  a  hard 
external  varnish,  such  as  is  found  on  the  outer  part  of  the  bamboo,  corn-stalk,  wheat-straw, 
etc.     It  gives  strength  and  protection  to  the  stalk. 

4.  Various  salts  of  potassium  and  lime  are  carried  through  the  plant  by  its  sap,  and 
some  of  them  are  finally  deposited  in  the  seed.     All  except  the  lowest  forms  contain  a  green 
coloring  matter  called  chlorophyl  (klo'ro-fll). 

1  A  few  of  the  lower  forms  of  animal  life  resemble  plants,  in  taking  their  food  by  absorption,  but  the  character  of 
the  food  is  different. 

2  Other  and  rarer  elements,  such  as  iodine,  bromine,  lithium,  etc.,  are  found  in  certain  plants. 


120 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


5.  The  seed  consists  mainly  of  starch,  with 
perhaps  more  or  less  of  oil.      The   seed-germ  is 
usually  rich  in  vegetable  albumen,  and  contains 
phosphorus  combined  with  lime   and  potassium. 
So  important  is  the  phosphorus,  that  without  it, 
the  seed  will  not  mature.     It  is  chiefly  the  lack 
of  phosphorus  that  causes  land  to  "wear  out." 

6.  Heat  is  likewise  necessary  to  the  develop- 
ment of  plants.     But  few  plants  will  germinate  if 
the  temperature  be  below  40°  F.,  while  many  perish 
when  the  temperature  falls  below  60°  F.  for  any 
length  of  time. 

7.  All  of  the  higher  plants  are  more  or  less 
dependent  upon  light  for  germination  and  growth. 
Certain  fungi,  and  plants  having  110  chlorophyl, 
however,  grow  best  in  the  dark. 

8.  Agents  of  Distribution. — In  the  distribu- 
tion   of   plant-life    over    large   areas  and  in  the 
perpetuation  of  many  species,  certain  agents  are 
constantly  at  work.      Of  these  agents  the  most 
important  are  winds,  running  water,  man,   ani- 
mals, and  insects. 

9.  Many  seeds,  such  as  the  dandelion  and  the 
thistle,  are  covered  with  a  soft  furze,  which  enables 
them  to  be  carried  to  a  great  distance  by  even  the 
gentlest  breeze. 

10.  The  maple  and  a  few  other  plants  have  winged  seeds,  which  are  carried  to  a 
great  distance  by  a  strong  wind.     Many  seeds,  such  as  the  chestnut  and  the  burr-clover,  are 
enveloped  in  a  cover  armed  with  thorns  or  spikes  which  tend  to  prevent  their  destruction 
by  animals,  and  thereby  increase  their  chances  of  perpetuation. 

11.  The  juicy  and  rich-colored  pulp  covering  many  seeds,  such  as  those  of  our 
common  orchard  fruit,  attracts  the  attention  of  birds  and  other  animals.     These  eat  the 
fruit  and  scatter  the  seeds  far  and  wide. 

12.  Nearly  all  seeds  are  provided  with  shells  or  coverings,  by  means  of  which  they 
float  upon   the  water.      Many  oak,   beech,    and  willow   groves  have  grown  from  seeds 
scattered  in  this  manner. 

13.  Insects  aid  in  the  distribution  of  a  few  plants,  as  the  fig,  yucca,  and  clover,  by 
fertilizing  the  flowers.     In  each  case,  the  insect,  while  taking  the  honey-dew  from  the 
flower,  smears  the  pistil  with  the  polleu  of  the  flower.1 

14.  Birds  convey  in  their  crops,  the  seeds  of  many  species  of  plants  to  distant  local- 
ities—even across  the  ocean.    Most  of  the  coral  islands  have  received  valuable  additions  to 
their  flora  in  this  manner. 


View  on  the  Amazon. 


Palma. 


1  The  flowers  of  our  common  clover  are  fertilized  by  the  humblebee. 
thrive  well  in  localities  where  the  humblebee  is  not  found. 


It  is  a  well-known  fact  that  clover  will  n<>i 


THE    DISTRIBUTION    OF    LIFE. 


121 


15.  By  far  the  greatest  distribution   of  plant-life  has  been  brought  about  by  man. 
Through  his  agency  all  of  the  food-producing  plants  have  been  scattered  over  the  world. 

16.  Effect  of  Climate. — All  countries  differ  in  the  plants  which  their  soils  produce, 
and  these  differences  are  owing  to  various  conditions  of  heat,  light,  and  moisture. 

17.  The  warm  and  moist  climate  of  the  Torrid  zone  favors  the  most  luxuriant 
growth  of  plants.     The  Colorado  desert,  equally  warm  but  destitute  of  moisture,  produces 
nothing  but  a  few  species  of  agave  (d-gd've)  and  cactus. 

18.  The  tundras  of  the  arctic  plains  suffer  no  lack  of  moisture;  but  the  low  tempera- 
ture, seldom  exceeding  35°  F.,  forbids  the  growth  of  anything  except  a  few  lichens. 

19.  Between  these  extremes  there  are  several  well-marked  belts  or  zones  of  vegetation. 
These  belts  correspond,  however,  with  isothermal  lines  rather  than  with  parallels  of  latitude. 
The  most  important  of  these 

belts  are  distinguished 
by  Alexander  von 
Humboldt  as 
follows : 


Mosses, 
Shrubs,  Birches,  . 


Cone-bearing  Trees,  Berries,  Potatoes, 
Deciduous  Trees,  Grain,  Tea,    .    . 

Evergreens,  Rice,  Vines,  Oranges,  Olives,     . 

Laurels,  Sugar-cane,  Cotton, 


Tree-ferns,  Date-palms,  Coffee,  Cocoa, 
Palms,  Bananas,  Spices,      .    .    .    .    , 


LATITUDE. 


Polar 


60  to  72 


45  to  65 


40  to  48 


80  to  45 


20  to  32 


15  to  25 


Equatorial 


TEMPERATURE. 


Below  32°  F. 


32°  to  45° 


40°  to  50° 


45°  to  60° 


55°  to  70° 


68°  to  75' 


73°  to  78° 


Above  73° 


Chart  showing  that  the  luxuriance  of  vegetation  diminishes  toward  the  poles. 
Trees  and  productions  of  the  zones. 


20.  Food-Plants.— 

The  most  important  and 
the  most  widely  spread  of 
all  plants  are  the  grasses. 
They  are  plentiful  in  near- 
ly every  part  of  the  world, 
excepting  the  polar  re- 
gions. They  also  include 
nearly  all  of  the  grains 
and  many  of  the  palms. 

21.  Wheat,  oats,  rice, 
barley,  and  rye,  are  na- 
tive  to    Asia,   and  were 
carried  from  thence  into 
the    new    world.      It    is 
asserted  that  the  grains 
have   never   grown   in  a 
wild  state. 


22.  Maize,  or  Indian  corn,  is  indigenous  to  the  new  world.     In  importance,  it  ranks 
next  to   wheat.      The   potato,   the   yam,    and   the  tobacco-plant   are   likewise   native  to 
America.     All  of  these  have  been  successfully  introduced  into  the  old  world. 

23.  Sugar-cane,  originally  from  China,  or  perhaps  India,  is  now  cultivated  in  nearly 
every  warm  country  in  the  world.     The  consumption  of  sugar  is  rapidly  increasing.     It  is 
produced  in  the  West  Indies,  the  southern  United  States,  the  Sandwich  Islands,  and  Brazil. 
Excellent  sugar  is  made  also  from  the  juice  of  the  beet. 

24.  Tea  and  Coffee.— The  cultivation  of  the  tea-plant  is  confined  to  China,  Japan, 
and  Farther  India.    There  are  two  varieties  of  the  plant;  but  from  the  same  kind  of  leaf, 
either  black  tea  or  green  tea  is  produced,  according  to  the  method  of  curing. 

25.  Coffee,  the  seed  of  the  fruit  borne  by  the  coffee-tree,  is  a  native  of  Abyssinia. 
The  Mocha  coffee  of  Arabia  is  considered  the  choicest.    Brazil,  the  West  Indies,  Central 
America,  and  Java  export  large  quantities.     Most  of  the  coffee  used  in  the  United  States 
comes  from  Brazil. 


122 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


A  Tea  Plantation  in  China. 


26.  The  spices,  al- 
most   without    excep- 
tion, come  from  Ma- 
laysia. 

27.  Cinchona,  one 

of  the  most  important 
medicinal  plants,  is  a 
native  of  South  Amer- 
ica.     From  this  tree, 
Peruvian    bark,     qui- 
nine, and  the  various 
salts  of  cinchona  (sin- 
ko'na)  are  ob- 
tained. 

28.  Opium, 
the  gum  ex- 
uding from 
the  seed-pod 
of  the  poppy, 

is  produced  in  China,  India,  and  various  other 

parts  of  southern  Asia. 


29.  In  the  tropical  regions,  the  food- 
plants  are  comprised  in  a  very  few  species. 
The  palms  yield  the  date,  cocoa,  and  sago. 
The  cassava  furnishes  tapioca,  the  principal 
food  of  the  South  American  Indians,  while 
the  bread-fruit  tree  yields  the  subsistence  of 

the   Polynesian.     The  absence  of  food-plants  from  a  country  forms  an  insurmountable 
barrier  to  the  existence  of  animal  life. 

30.  Starch  and  gluten  constitute  the  elements  of  nutrition  in  nearly  all  of   the 
foregoing  food-plants.      Their  seeds  are  always  very  rich  in  phosphorus,  oil,  and  other 
substances  required  by  the  animal  body. 

31.  Textile  Fiber  Plants. — The  plants  producing 
cloths  and  textile  fabrics  are  as  widely  cultivated  as  the 
food-plants.  Cotton,  the  chief  of  these,  is  thought  to 
be  a  native  of  India,  but  it  is  probable  that  its  use 
precedes  our  historical  knowledge  of  it.  From  the 
United  States,  China,  and  India,  the  greatest  quantities 
are  obtained,  but  it  is  cultivated  in  nearly  all  warm 
countries. 


A  Coffee  Plantation  in  Brazil. 


32.  Flax,  a  plant  native  to  Europe,  produces  the 
beautiful  white  fibre  of  linen  cloth.  It  is  now  widely 
cultivated  in  the  United  States  and  other  countries. 
Hemp,  ramee,  and  jute  are  native  to  India ;  their  fiber 

is  much  used  for  coarser  cloth  and  for  cordage.     From  India,  their  cultivation  has  been 

introduced  into  Europe  and  America. 


A  Cotton  Plantation. 


THE    DISTRIBUTION    OF    LIFE. 


123 


33.  Distribution   of  Animals.^ The   same   conditions   of  climate  which  have 
been  so  powerful  in   controlling  the  distribution  of  plant-life,   have 

been  equally  powerful  in  fixing  the  boundaries  of  animal-species. 

34.  Each  grand  division  of  the  world  is   represented  by 
some   particular    form  of    life  which   is   not   characteristic 
elsewhere,    and    which,    as    a    general    law,    is    not 
adapted  to  life  and  growth  in  other  countries. 

35.  Thus,  in  Europe  and  Asia,  we   find 
the  cud-chewing  animals  ;  in  North  Amer- 
ica, there  are  the  birds  of  passage ; 

South  America  is  distinguished  for 
its  toothless  species  ;  while  the  mar- 
supials or  pouched  animals  are  con- 
fined almost  exclusively  to  the  Aus- 
tralian continent. 

36.  We  find,  also,  that  in  past 
ages  many  species  of  animals  have 
disappeared,   and  that  their  places 
have    been    taken    by    others.      In 
nearly  every  instance,  the  succeed- 
ing types  have  differed  slightly  from 
those  preceding.     Nearly  always,  the 
later  types  have  been  the  superior. 

Reindeer. 

37.  Of  the  many  thousand  species 
of  animals   existing  on   the  Earth, 
but  a  very  few  are  of  use  either  as 
food  or  as  beasts  of  burden. 

38.  In   the    northern  regions, 

the  reindeer  of  the  old  world,  in 
this  respect,  stands  first.  In  the 
western  hemisphere,  his  place  as  a 
beast  of  burden  is  partly  supplied 
by  the  Esquimau  dog. 

39.  Seal  blubber  and  fish  furnish 
about    the    only  sustenance    to  the 
natives    of    the    northern    lands   of 
the   American    continent,   many  of 
whom  know  no  other  food. 

40.  In    the    Temperate    zone, 

the  horse,  ox,  hog,  and  sheep  are 
the  most  important  domestic  ani- 
mals. These  have  been  distributed 
by  the  agency  of  man  throughout 
Lassoing  wild  Horees.  the  habitable  parts  of  the  globe. 


124 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


41.  All  of  these  animals  are  probably  natives  of  Asia,  and 
have  accompanied  man  in  his  migrations.     They  are  hardy,  and 
thrive  wherever  the  grasses  are  found. 

42.  In  tropical  regions,  the  camel  and  the  elephant  are 
much  used  as  beasts  of  burden.     The  former  has  been  used  in 
the  desert  regions  of  the  United  States,  in  this  capacity. 

43.  Of  domesticated  birds  used  by  mankind,  the  number 
of  species  is  still  less  and  comprises  scarcely  any  except  the 
ordinary  barnyard  fowl  and  the  ostrich.     Most  of  these  are 
abundant  in  a  wild  state. 

44.  The  fur-bearing  animals 
are  wild,   and    are   natives  of   the 
colder  regions.     They  comprise  the 
fur  seal,  beaver,  otter,  sable,  stone 
marten,  ermine,  and  mink.     The  fur 
seal  is  the  most  important. 

45.  The   bee   and   the    silk- 
worm   have   been   distributed   far 
and  wide,   through  the    agency  of 
man.      So  important   are   these  in- 
sects,  that    throughout    the   world, 
they  are  protected  by  national  laws. 
In  China,  Japan,  France,  and  Italy, 
the  culture  of  the  silk-worm  ranks 
among  the  most  important    indus- 
tries. 

46.  The  two  hemispheres  pre- 
sent many  points  of    difference,  in 
respect  to  their  zoology.     The  lion, 
the  tiger,  the  leopard,  and  the  hyena 

are  unknown  on  the  American  continent.  Here,the  tiger  is  represented  by  the  panther,  the 
puma,  and  the  wild  cat.  The  carnivorous  animals  of  the  new  world  are  fewer  in  species  and 
smaller  than  those  of  the  old. 

47.  The  elephant  is  found  in  the  tropical  regions  of  Asia  and  Africa,  but  the  species 
of  the  two  continents  differ,  in  many  respects.    This  animal  has  no  representative  in  the 
Western  Hemisphere. 

48.  The  rhinoceros  is  also  found  in  Asia  and  Africa,  but  does  not  exist  elsewhere. 
The  hippopotamus  is  confined  to  a  limited  part  of  Africa,  being  found  in  the  region  of  the 
Nile  river  only. 

49.  The  walrus  and  the  polar  bear  are  found  in  the  cold  regions  of  both  hemispheres. 
The  former  is  amphibious,  and  its  distribution  is  limited  by  temperature  only.     The  polar 
bear  is  not  only  an  expert  swimmer,  but  also  an  inhabitant  of  floating  ice  packs. 

wide  distribution  in  these  regions. 

50  Several  species  of  bear  are  found  in  the  mountainous  regions  of  the  North  Tem- 
perate zone.  Those  of  the  two  hemispheres  differ  but  slightly.  The  grizzly  bear  is  found 
in  the  Rocky  mountains  only  ;  the  black  bear  is  distributed  over  North  America. 


Camel  Caravan. 


125 


51.  The  dog  and  the  wolf  are 
found   in  about  the  same  latitudes 
throughout    the  world.     There    are 
many  species,  but  they  do  not  differ 
much  from  one  another. 

52.  Reptiles    and   snakes  are 
most  numerous  in  the  moist,  tropical 
regions,  but  gradually  disappear  in 
the  higher  latitudes.     Their  species 
in  both  hemispheres  are  similar. 

53.  Monkeys  are  also  abundant 
in  all  tropical  regions  of  the  world. 
There  are  many  species  of  them,  but 
those  of  the  Eastern  and  Western 
Hemispheres  are  very  distinct. 

54.  Those  of  the  American  con- 
tinent are  small  and  more  closely 
resemble  quadrupeds.     With  the  ex- 
ception of  one  species  they  possess 
tails.    The  monkeys  of  the  old  world 
are  larger,  and  usually  tailless. 


The  Bhinocerc 


The  Monkey-bridge. 

55.  The  zoology  of  Australia 

is  unlike  that  of  any  other  part  of 
the  world.  But  few  species  of  ani- 
mals existing  in  other  parts  of  the 
world  are  found  here,  and  these,  for 
the  greater  part,  are  birds.  The  ani- 
mals are  generally  marsupials  or 
pouched  animals. 

56.  The  eagle,  hawk,  owl,  par- 
rot, and  Australian  ostrich  do  not 
differ  greatly  from  those   of   other 
continents.    The  opossum  resembles 
that  of  North  America  in  structure 
and  habits. 

57.  The  kangaroo,  of  which 
there  are  many  species,  is  not  found 
in  any  other  part  of  the  world.    The 
ornithorhyncus,   an  animal    having 
the  body  of  an  otter  with  a  head  like 
that  of  a  duck,  is  also  peculiar  to 
Australia. 


126 


MONTEITH'S    NEW   PHYSICAL     GEOGRAPHY. 


58.  The  preceding   paragraphs 
serve  to  show  that  climatic  regions 
constitute  the  centers   from  which 
the  various    forms  of    animal   and 
plant  life  have  spread. 

59.  The    territories    frequently 
overlap  one  another,  but  each  region 
is  still    a  strongly  marked    center, 
and  wherever   its    life-forms    have 
changed,  the  change  is  due  usually 
to  the  agency  of  man. 

60.  Those    changes    in    animal 
life    and    habits  which    have    been 
wrought  by  the  agency  of  man,  con- 
stitute the  best  of  proofs  that  the 
laws  of  nature  operate  not  only  in  a 
similar  manner,  but  also  on  a  stupen- 
dous scale  as  well. 


The  Black  Bear. 

61.  So  exacting  are  these  laws, 
that    neither  evasion   nor  disobedi- 
ence is  tolerated.     A  failure  to  con- 
form to  them    is    followed    by   the 
death  of  the  individual  or  even  the 
extinction  of  the  whole  species. 

62.  The   Human  Race.  — The 
population  of  the  Earth  is  estimated 
at   about    1,461,000,000    people,   who 
occupy  every  part  of  its  land  surface 
except  the  polar  regions.     Their  dis- 
tribution is  shown  in  the  following 
table : 


GRAND  DIVISIONS. 

POPULATI'N. 

POP. 

TO  1 

SQ.M 

Asia  

835  000  000 

47 

Europe  

318  000  000 

86 

Africa  

206  000  000 

16 

North  America  

73  000  000 

8 

South  America  

25  000  000 

4 

Australia  &  Oceanica 

4,000,000 

1 

63.  For  convenience  they  are 
grouped  into  five  races,  the  Cau- 
casian, Mongolian,  Black,  Red,  and 
Malay. 


The  Lion. 


THE    DISTRIBUTION    OF    LIFE. 


127 


The  Caucasian  Rice  ;  Egyptian,  Arab,  Abyssinian,  European. 


64.  The  Malays  and  the  Ameri- 
can Indians  are  by  many  considered 
as  separate  races ;  by  others  they  are 
classed  among  the  Mongolians,  to 
whom  they  bear  a  strong   resem- 
blance in  structure  and  in  language.1 

65.  The  Mongolian  is  the  yel- 
low race.     The  distinctive  features 
are  :  black  eyes,  straight  black  hair, 
a  flat  nose,  and  usually  a  yellow 
skin. 

66.  This  race  includes  the  Chi- 
nese, Japanese,  Tartars,   Burmese, 

Siamese,  and  Turks,  of  Asia  ;  the  Lapps,  Finns,  and  Magyars  (mod'jors),  of  Europe  ;  and  the 
Esquimaux,  of  America.     The  Turks  and  Circassians  have  white  skins. 

67.  The  Caucasians  are  more  widely  diffused  than  any  other  race.      They  are  dis- 
tinguished by  a  skin  varying  from  white  to  dusky  brown,  black  or  brown  hair,  and  gray  or 
brown  eyes.     The  most  noticeable  characteristic  is  the  high  forehead  and  oval  skull. 

68.  The  Caucasian  race  has  colonized  Europe,  America,  and  northern  Africa.     This  race 
exists  in  Hindostan  and  portions  of  Asia,  where  it  seems  to  have  originated. 

69.  The  Malays  bear  a  close  resemblance  to  the  Mongols,  having,  however,  a  brown 
skin.     They  inhabit  most  of  the  islands  of  Malaysia. 

70.  The  Negro  or  black  race  is  distinguished  by  a  black  skin,  black  eyes,  black,  woolly 
hair,  thick, protruding  lips,  high  cheek  bones,  and  a  broad,  flat  nose. 

71.  The  Negroes  are  native  to  central  Africa  and  a  chain  of  islands  of  which  New  Guinea 

is  the  largest.  About  six  million  peo- 
ple of  this  race  are  found  in  the  United 
States  and  the  West  Indies. 

72.  The  American  Indians,  or 

copper-colored  race,  are  also  related  to 
the  Mongolians.  Those  of  the  Pacific 
coast  of  North  America  are  clearly  of 
Mongolian  origin.  They  are  distin- 
guished by  a  skin  varying  from  red- 
dish to  dusky  brown,  black  eyes  and 
hair,  and  high  cheek  bones. 

73.  Indians  formerly  occupied  the 
most  of  the  American  continent.     In 
North  America, they  are  rapidly  disap- 
pearing.    In  South  America,they  have 
intermarried  with  Caucasian  colonists, 
and  are  becoming  a  powerful  people. 


Mongolian  or  Yellow  Race  ;  Esquimaux  and  Chinese. 


1  This  classification  is  both  unsatisfactory  and  unscientific,  but  no  system  meeting  with  general  adoption  has  yet 
been  proposed.  With  the  present  system,  the  inhabitants  of  Caucasia  are  made  the  type  of  the  race.  Late  investigations 
have  shown  that  these  people  are  of  Mongolian  descent. 


128 


MONTE ITH'S    NEW    PHYSICAL     GEOGRAPHY. 


The  Malay  Race  ;  Sandwich  Islanders  and  New  Zealauders. 


74.  The  physical  difference  in 
the   people   composing   the  human 
race  is  wide.     By  those  who  believe 
in  the  common  origin  of  the  race, 
it  is  asserted  that  these  differences 
are  due  to  climate,  food,  and  man- 
ner of  living. 

75.  Causes  of  Difference  in 
Development. — The  general  con- 
dition of  a  people    depends  much 
upon  their  manner  of  living,  and 
this  in  turn  is  governed  by  climate. 
A  people  living  in  a  country  where 
their  wants  are  supplied  without  ex- 
ertion, are  not  likely  to  become  a 
powerful  nation. 

76.  On  the  contrary,  if  a  rigorous  climate  requires  the  skill  of  body  and  brain  to  obtain 
those  things  necessary  to  sustain  life,  such  a  people  are  apt,  in  the  course  of  generations,  to 
become  powerful. 

77.  It  is  the  struggle  for  existence  that  develops  not  only  the  body,  but  the  mind 
of  man  as  well ;  and  it  is  this  struggle  that  has  caused  mankind  to  associate  in  clans  and  to 
organize  institutions  for  mutual  protection  and  support. 

78.  In  the  North   Temperate   zone,  the  conditions  are  best  suited  to  physical  and 
intellectual  development.   Here  the  battle  with  hunger  has  awakened  man's  dormant  powers. 

79.  To  insure  his  existence, he  is  compelled  to  exercise  both  hand  and  mind.     But  even 
these  are  not  enough,  and  the  subjugated  forces  of  nature  perform  the  tasks  to  which  his 
own  strength  is  unequal. 

80.  No  exact  date  can  be  assigned  to  the  first  appearance  of  man  upon  the  Earth.     His 
early  history  is  unwritten  and  un- 
known.    The   geological  evidences 

are  too  meager  to  furnish  any  satis- 
factory clue  to  his  history,  socially 
or  intellectually. 

81.  They  show,  however,  that 
primeval  man  dwelt  in  caves,  that 
he  followed  the  chase,  that  he  used 
weapons,  that  he  wore  rude  orna- 
ments, and  that  he  had  learned  the 
use  of  fire. 

82.  Knowing  the  use  of  fire, 

his  civilization  was  a  certainty,  and 
henceforth,  guided  by  the  hand  of 
an  All-wise  Creator,  his  path  lay  in 

the  Way  Of  light.  The  Black  Race. 


THE    DISTRIBUTION    OF    LIFE. 


129 


83.  With    the    appearance    of 
man,  the  long  succession  of  steps  in 
the  creation  of  life-forms  seems  to 
have  ceased.     His  coming  was  the 
culminating  act  of  creation. 

84.  Physical  development  had 
reached  its  highest  plane,  and  intel- 
lectual development  began  its  sway. 
The  reign  of  matter  ended,  and  that 
of  mind  began. 

85.  The  Earth  was  made  as  a 
dwelling-place  for  man.      Its    day 
and  night,  land  and  water,  air  and 
clouds,  seed-time  and  harvest,  for- 
ests and  mines, — all  contribute  to 
his  comfort  and  well-being. 


American  Indians,  or  Red  Race. 


WHAT  HAS  BEEN  TAUGHT  IK  CHAPTER  XIX. 


TJie  food  of  plants  consists  of  water,  carbon, 
hydrogen,  oxygen,  silicon,  potassium,  lime,  and 
phosphorus. 

Variations  of  these  elements  are  the  cause  of 
great  diversity  in  the  distribution  of  plants. 

The  distribution  of  plants  is  accomplished  by 
'winds,  ^vater,  birds,  insects,  and  man. 

The  chief  food-plants  belong  to  the  palms 
and  the  grasses.  They  are  native  to  Asia,  and 
their  distribution  has  accompanied  the  migra- 
tions of  man. 

The  laws  governing  the  distribution  of  plants 
also  govern  the  distribution  of  animals. 

Compared  with  the  number  of  plants,  but 
few  species  of  animals  are  serviceable  to  man. 

In  northern  latitudes,  the  reindeer  ranks  first 
as  a  beast  of  burden  and  a  source  of  food. 

In  the  Temperate  zones,  the  horse,  ox,  sheep, 
and  hog,  all  natives  of  the  old  world,  are  valu- 
able sources  of  food  and  clothing. 

The  silk-worm  and  the  honey-bee  have  been 
distributed  over  the  world  by  the  agency  of  man. 

TJte  elephant  is  a  native  of  both  Africa  and 
Asia,  the  two  species  being  distinct,  and  having 
no  representatives  on  the  American  continent. 

The  hippopotamus  is  confined  to  a  small  por- 
tion of  Africa. 


The  bear,  walrus,  and  wolf  are  found  in  the 
northern  belt  throughout  the  world. 

The  monkeys  of  the  old  world  are  larger,  and 
more  closely  resemble  the  human  species  than 
those  of  the  new. 

Each  climatic  region  is  a  center  from  which 
animals  peculiar  to  that  region  have  radiated. 

The  population  of  the  Earth,  consisting  of 
one  and  a  half  billion  people,  are  classified  as 
Caucasian,  Mongolian,  Black,  Red,  and  Malay. 

The  Mongolian,  or  yellow  race,  inhabits  parts 
of  Asia s  Europe,  and  America. 

The  Caucasian  race  has  colonized  Europe, 
America,  and  Africa,  and  occupies  the  southern 
part  of  Asia. 

The  Negro,  or  black  race,  inhabits  central 
Africa,  and  a  part  of  the  Malaysian  archipelago. 

The  Malays  (considered  by  some  authorities,  a 
division  of  the  Mongolian  race)  are  confined  to 
the  Malay  Peninsula,  Malaysia,  and  Polynesia. 

The  American  Indians  are  found  only  in  the 
American  continent. 

Tfie  races  differ,  not  only  in  color  of  skin,  but 
also  in  the  shape  of  skull,  color  of  hair  and  eyes, 
and  in  language. 

In  the  North  Temperate  zone,  the  conditions 
are  most  favorable  to  the  development  of  man. 


130 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


CHAPTER     XX. 


THE     DISTRIBUTION      OF     M  1  1ST  E  Ft 


1.  The  geographical  distribution  of  minerals  is  not  only 
closely  connected  with  the  establishment  of  manufacturing 
and  other  industries,  but  it  has  also  had  much  to  do  with 
the  development  and  civilization  of  mankind. 

2.  The  earliest  history  of  the  human  race  is  associated 
with  implements  and  tools  made  of  mineral  substances  ;  the 
earliest  written  history  begins  with  the  use  of  metals. 

3.  The  chief  mineral  deposits  are  in  the  mountains  and 
highlands.     Coal,  however,  is  found,  to  a  great  extent,  in 
lowlands.     The  mineral  resources  considered  in  this  chapter 
are  metals  and  their  ores,  besides  fuel,  building  stones,  and 
gems. 

4.  Iron. — Iron  is  more  closely  connected  with  the  civil- 
ization of  the  human  race  than  is  any  other  substance  found  in 
the  Earth.     It  is  the  most  widely  diffused  and,  at  the  same  time,  the 
most  abundant  of  all  the  metals. 

5.  The  ores  of  iron  are  abundant  in  the  mountainous  regions  of  nearly  every  part  of  the 
world.     In  the  United  States,  the  Appalachian  mountain  system  is  the  center  of  production, 
although  it  is  widely  distributed  throughout  both  the  eastern  and  the  western  highlands. 

6.  Steel,  which  is  prepared  from  iron,  is  fast  supplanting  it  for  most  purposes.     The 
value  of  the  iron  and  steel  manufactures  in  the  United  States  exceeds  300,000,000  dollars 
yearly.     The  most  abundant  ore  of  iron  is  known  as  hematite. 

?.  Copper. — Copper  preceded  all  other  metals  used  by  man.  It  is  found  in  nearly  all 
highland  regions.  In  the  United  States,  the  largest  deposits  are  found  in  the  Pacific  High- 
lands and  in  the  vicinity  of  Lake  Superior.  The  chief  ores  from  which  it  is  obtained  are 
malachite,  a  carbonate,  and  copper  glance,  a  sulphide. 

8.  Tin.— Tin  is  found  in  but  few  localities,  the  chief  sources  being  Cornwall,  England, 
the  island  of  Banca,  Malacca,  and  Australia.     There  are  also  valuable  mines  in  California 
and  Mexico.     The  total  yearly  production  in  the  world  is  about  34,000  tons. 

9.  Zinc. — This  metal  is  abundant  in  many  parts  of  Europe  and  America.     The  mines 
of  Silesia  and  Freiberg,  in  Europe,  and  those  of  Pennsylvania  and  New  Jersey  are  the  most 
productive. 

10.  Lead.— The  lead  mines  of  the  world  are  found  both  in  plains  and  highlands.     The 
ore  from  which  lead  is  extracted  is  galena,  a  combination  of  sulphur  and  lead. 

11.  Lead  is  found  in  nearly  every  country  of  Europe  and  Asia.     The  most  extensive 
deposits  of  the  United  States  are  in  Colorado,  Nevada,  and  Arizona.     There  are,  also,  very 
productive  mines  in  Missouri,  Wisconsin,  and  Illinois. 


THE    DISTRIBU1ION    OF    MINERALS. 


131 


A  Silver  Mine  and  Mill. 


12.  Silver 

is  about  as 
widely 
dissemi- 
nated    as 
gold,    but 
is  found  in 
much  lar- 
ger quan- 
tities. Like 
gold,    its   use 
dates    back    to 
the  beginning  of 
written  history  ;  un- 
like gold,  it  is  rarely 
found     as    a    metal, 
and  therefore  is  not 
found  in  alluvial  soils. 


Mining  Flumes  for  Conducting  Water. 


13.  Silver  occurs  in  nearly  every  mountain  or  highland  system  in  the  world.     It  is 
usually  combined  with  either  sulphur  (silver  glance)  or  chlorine  (horn  silver)  •  it  is  always 
associated  with  lead,  and  frequently  with  copper,  antimony,  and  arsenic. 

14.  In  the  United  States,  the  chief  sources  are  the  mines  of  Colorado,  Nevada,  Utah, 
Montana,  and  Arizona.   The  mines  of  the  Comstock  lode  in  Nevada  for  many  years  produced 
nearly  as  much  as  the  combined  amount  of  all  the  other  mines  of  the  world. 

15.  Gold. — Gold  is  one  of  the  most  widely,  although  sparingly,  disseminated  metals.    It 
is  found  in  all  soils,  granitic  rocks,  and  in  sea  water.    The  chief  deposits,  however,  are  in  the 
quartz  veins  and  the  ancient  river  beds  of  the  Pacific  Highlands  and  Georgia.     The  African 
and  the  Australian  gold  fields  have  also  produced  much  gold. 

1C.  Gold  is  found  in  a  metallic  state,  but  it  is  never  pure,  being  alloyed  usually  with 
«ilver  and  platinum.  The  luster  of  gold,  its  malleability,  its  ductility,  and  its  resistance  to 
the  strongest  acids,  give  it  a  high  intrinsic  value. 

17.  There  are  many  reasons  to  believe  that  the  gold  and  silver  found  in  quartz  veins 
were  dissolved   from  igneous  rocks  by  hot  water.     Water   under  great  pressure  may  be 
heated  several  hundred  degrees  above  the  boiling  point,  and  it  will  then  dissolve  many  min- 
eral substances  which  it  would  not  otherwise. 

18.  As  the  hot  water  is  pressed  upward  through  the  crevices  in  the  rocks,  it  becomes 
cooler  and  can  no  longer  hold  these  substances  in  solution.     The  silica  is  deposited  on  the 
sides  of  the  crevices  as  quartz,  and  with  it  the  various  metallic  substances  of  which  metallic 
iron,  copper,  gold,  and  silver  are  the  principal.     Finally,  the  crevice  is  entirely  filled,  and  a 
quartz  vein  is  formed. 

19.  Nickel. — Nickel,  which  until  lately  has  been  considered  one  of  the  rarer  metals,  is 
now  one  of  the  most  extensively  used.     It  is  as  hard  and  infusible  as  iron,  does  not  blacken 
nor  corrode,  and  its  luster  surpasses  that  of  silver. 

20.  This  metal  has  almost  entirely  superseded  silver  for  plating  purposes.     It  is  found 
in  Sweden,  Spain,  and  Germany.     The  mines  of  Pennsylvania  are  the  chief  source  in  the 
United  States.     Those  of  Lovelock,  Nevada,  are  extensive. 


132  MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 

21.  Quicksilver. — This  metal,  also  called  mercury,  is  the  only  one  existing  as  a  liquid 
at  ordinary  temperatures.     There  are  but  few  productive  mines  known.     Those  of  Almaden, 
Spain,  and  New  Almaden,  California,  supply  four-fifths  of  the  amount  used.     Cinnabar,  a 
sulphide,  is  the  ore  from  which  it  is  usually  obtained. 

22.  Other  Metals. — Many  of  the  metals  least  known  are  the  most  widely  distributed. 
Such,  for  instance,  are  sodium,  the  base  of  common  salt;   potassium,  the  base  of  potash 
salts  ;  calcium,  the  base  of  lime. 

23.  Aluminium,  the  base  of  common  clay,  is  a  valuable  metal,  but  the  cost  of  extracting 
it  has  prevented  its  use.     Platinum,  iridium,  and  osmium  are  usually  associated  with  gold. 
Platinum  is  valuable  on  account  of  its  infusibility. 

24.  Precious  Stones. — Of  the  precious  stones,  the  diamond  has  for  many  centuries 
been  the  most  admired  and  generally  the  costliest.     The  diamond  is  pure  carbon  in  a  crys- 
talline form,  and  the  hardest  mineral  known.     The  alluvial  deposits  of  South  Africa  and 
Brazil  have  furnished  the  greatest  number. 

25.  Rubies  and  sapphires  are  oxides  of  aluminium.     The  color  is  due  to  the  presence 
of  other  mineral  substances.      The  red  variety  is  called  the  ruby,  the  blue  is  known  as 
sapphire.     Faultless  stones  rank  next  in  value  to  the  diamond. 

26.  Emerald  or  beryl,  is  also  a  gem  of  which  aluminium  is  the  base.     The  beautiful 
green  color  is  due  to  a  small  amount  of  chromium  oxide.     Emeralds,  rubies,  and  garnets  are 
found  in  granite  rocks  and  slate. 

27.  Topaz  is  also  a  gem  having  an  aluminium  base.     It  varies  much  in  color,  but  the 
wine-colored  topaz  of   Saxony  is  the  most  highly  prized.      The  mountains  of   Brazil  and 
Siberia  furnish  the  greatest  supply. 

28.  Quartz,  frequently  called  silica,  furnishes  by  far  the  largest  variety  of  gems.     Of 
these  the  opal  is  the  most  valuable.     It  differs  from  common  quartz  in  containing  water  of 
crystallization. 

29.  Amethyst    is    quartz    colored    pink   or  purple   by  traces   of    manganese   oxide. 
Agate  and  chalcedony  (kal-sed'o-ny)  are  quartz  with  variously-colored  layers.     Carnelian 
and  sar'donyx  are  red,  semi-transparent  varieties  of  quartz  colored  with  oxide  of  iron. 

30.  Jasper  and  bloodstone  are  opaque  varieties  of  quartz  mottled  with  salts  of  iron, 
nickel,  and  manganese.     All  of  these  are  abundant  in  mountainous  regions.     Onyx  is  a 
variety  of  quartz,  having  alternate  black  and  white  bands. 

31.  Turquoise    (tur-koiz),   malachite    (mal'a-kite),   and    chrys'ocolla  are  minerals 
having  a  copper  base.     The  first  is  obtained  in  Persia  and  New  Mexico,  the  last  two  in  the 
Ural  mountains  and  the  Pacific  Highlands. 

32.  Coal.— Coal,   although  of  vegetable  origin,   is  classed  among  the  minerals.     In 
form  and  position,  the  coal-beds  do  not  differ  from  the  stratified  rocks  of  which  they  are 
an  example. 

33.  Like  other  stratified  rocks,  the  coal-beds  have  been  formed  in  the  presence  of  water. 
But  unlike  them,  the  coal-seams  consist  of  layers  of  half  decomposed  vegetable  matter,  such  as 
twigs,  leaves,  rootlets,  and  the  trunks  and  roots  of  trees,  instead  of  accumulations  of  sediment. 

34.  There  are  two.  ways  in  which  most  of  the  vegetable  matter  forming  the  coal-beds 
accumulated.     It  may  have  grown  in  place,  or  it  may  have  been  deposited  at  the  mouths  of 
rivers,  having  been  carried  there  by  the  river  itself. 


THE    DISTRIBUTION    OF    MINERALS.  133 

35.  In  the  first  case,  what  are  now  coal-beds  were  formerly  immense  peat  swamps. 
In  fact,  there  are  peat  swamps  in  various  parts  of  the  world  at  the  present  time,  in  which 
the  half -decomposed  vegetable  matter  that  has  accumulated  in  the  swamp,  is  undergoing 
the  first  steps  of  its  change  to  coal. 

36.  Such  swamps  are  common  in  all  parts  of  the  world,  especially  in  northern  countries. 
One-tenth  of  the  area  of  Ireland  is  covered  with  them.    They  are  common  in  parts  of  France, 
Switzerland,  the  New  England  states,  and  the  Dominion  of  Canada. 

37.  Peat  may  be  any  vegetable  substance ;  but  it  usually  applies  to  the  remains  of  certain 
species  of  mosses  which,  dying  at  one  end,  retain  life  and  grow  at  the  other.     Frequently, 
accumulations  are  thirty  or  forty  feet  in  thickness. 

38.  The  next  step  in  coal-making  was  the  sinking  of  the  peat  swamp  or  other  accu- 
mulations of  vegetable  matter,  below  the  sea-level.    After  this  had  occurred,  the  water  gradu- 
ally covered  it  with  sand  and  mud,  burying  it  many  feet  deep. 

39.  The  great  weight  of  the  sediment  spread  over  the  swamp  pressed  it  into  a  flat 
layer  or  seam  ;  this  pressure  generated  heat,  and  the  partial  decomposition  of  the  vegetable 
matter  generated  still  more.    In  the  course  of  time,  the  combined  action  of  heat  and  moisture 
changed  the  substance  to  coal.1 

40.  Often  the  same  processes  of  accumulation,  submergence,  and  partial  combustion 
have  taken  place  again  and  again,  until,  in  some  localities,  there  are  more  than  one  hundred 
distinct  seams  of  coal.     In  the  United  States,  the  coal-forming  process  did  not  cease  until  the 
upheaval  of  the  Appalachian  mountains  lifted  the  coal-beds  high  above  the  sea-level. 

41.  The  varieties  of  coal  differ  much  in  appearance  and  composition.     They  include 
mineral  oil  (petroleum),  mineral  pitch  (asphaltum),  lignite,  brown  coal,  cannel2  coal  (and 
shales),  jet,  bituminous  or  soft  coal,  anthracite  or  stone  coal,  and  graphite.     The  latter  is  an 
infusible  form  of  carbon,  and  is  classed  along  with  coal  on  account  of  its  origin. 

42.  It  is  thought  that  the  difference  in  varieties  of  coal  is  owing  to  varying  degrees  of 
pressure  and  heat.     Whenever  the  pressure  was  great  and  the  temperature  high,  the  volatile 
matter  was  driven  off  and  thereby  converted  the  bituminous  and  fat  coal  into  anthracite. 

43.  In  older  rocks,  there  is  evidence  that  the  pressure  has  been  much  greater  and  the 
temperature  higher.     As  a  result,  the  coal  or  carbon  is  found  in  the  form  of  graphite,  the 
so-called  black  lead  of  commerce. 

44.  Distribution. — Coal  is  found  usually  in  the  rocks  of  the  Carboniferous  Age  (see 
p.  16),  of  which  it  is  the  chief  feature.     There  are  also  large  deposits  of  coal  in  the  rocks  of 
the  Tertiary  Age,  which  are  usually  called  cretaceous  coals.     Coal  fields  are  more  or  less 
abundant  wherever  the  rocks  of  these  geological  ages  reach  to  the  surface. 

45.  The  total  area  of  these  fields  exceeds  200,000  square  miles.     Of  this  area,  150,000 
square  miles  are  in  the  United  States,  18,000  square  miles  are  in  the  Dominion  of  Canada,  and 
12,000  square  miles,  in  Great  Britain.   The  other  fields  are  chiefly  in  Spain,  France,  Germany, 
and  Belgium. 

1  Coal  has  been  formed  artificially  by  subjecting  wet  sawdust  to  pressure  and  heat. 

*  A  corruption  of  candle.  Bituminous,  cannel,  and  other  fat  coals  also  contain  much  oxygen.  Brown  coal  and  lignite 
are  imperfectly  formed  coals.  Often  coal  of  this  kind  contains  stumps  and  trunks  of  trees,  sorretimes  unaltered,  but  quite 
frequently  partly  converted  into  coal. 


134 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Salt  Mines  of  Wieliczka  (we-litch'ka),  near  Cracow,  Austria. 


46.  The  coal  fields  of  North 
America     comprise     the    border 
fields  of  Rhode  Island  and  Nova 
Scotia ;    the  Alleghany  fields  of 
the  Appalachian  Highlands  ;  the 
interior  fields  of  Michigan,  Illi- 
nois,  Missouri,    and    Iowa;    and 
the  Arctic  fields  of  Melville  island 
and  vicinity.      Tertiary    coal    is 
abundant  on  the  Pacific  coast. 

47.  Petroleum. — Mineral  oil 
or  petroleum  is  also  a  product  of 
vegetable  matter.    The  process  of 
formation  is  similar  to  that  of  the 
coal  deposits.     It  is  probable  that 
mineral  oil  has  been  formed  only 
when  the  decaying  matter  was 
deposited  in  salt  marshes. 

48.  The  best  known  oil  regions  are  those  of  Pennsylvania  and  Canada.     The  oil  fields 
of  southern  California,  however,  are  thought  to  be  the  most  extensive  at  present  known. 

49.  Building1  Stones. — The  building  stones  most  commonly  used  are  granites,  sand- 
stones, and  limestones.     Each  class  of  these  rocks  contains  many  varieties  ;  but  only  those 
which  are  strong  and  do  not  crumble  by  exposure,  are  useful. 

50.  Granite  is  in  many  respects  the  best  of  all  building  stone.    Much  of  the  so-called 
granite  is  either  gneiss  (nice)  or  syenite  (see  p.  14).     Granitic  rocks  are  common  in  nearly  all 
mountain  ranges,  having  been  thrust  upward  through  the  stratified  rock. 

51.  Granite  is  usually  of  a  grayish-white  color,  but  syenitic  varieties  are  often  very  dark. 
There  are  immense  deposits  in  New  Hampshire  and  Vermont.    The  red  granite  of  the  Rocky 
mountains  is  highly  prized. 

52.  Sandstones  are  just  what  their  name  indicates — rock  composed  of  sand.     There 
must  be  some  cement  (sem'enf),  however,  to  unite  the  grains  of  sand  into  rock. 

53.  The  cement  is  usually  either  iron  oxide  or  lime.     The  latter  forms  a  white  or  gray 
sandstone,  while  the  former  are  usually  reddish-brown.   The  durability  of  this  stone  depends 
on  the  proportion  of  the  cement. 

54.  This  variety  of  building  stone  is  found  in  all  continental  divisions  of  land,  being 
most  common  in  the  foot-hills  of  mountain  ranges,  especially  on  that  mountain  slope  which 
faces  the  sea.     "Brown  stone"  and  "old  red"  sandstone  are  well  known  varieties. 

55.  Limestone  is  a  stratified  rock,  and  therefore  water-formed.     Of  the  three  com- 
monest forms,  chalk,  gray  limestone,  and  marble,  the  latter  two  only  are  serviceable  as 
building  stones.   The  gray  limestones  are  found  chiefly  in  old  marine  plains.    There  are  large 
deposits  in  the  Mississippi  valley,  where  the  rock  is  known  as  "Athens  marble,"  "  Niagara 
limestone,"  "  gray  stone,"  etc. 

56.  Marble  is  also  a  stratified  rock,  which  does  not  differ  in  composition  from  the  gray 
limestones.     In  appearance,  it  is  commonly  much  whiter,  although  it  is  often  beautifullv 
streaked  with  gray,  or  mottled  with  variously  colored  spots. 


THE    DISTRIBUTION    OF    MINERALS. 


57.  Marble  is  a  metamorphic  limestone — that  is,  common  limestone  changed  by  pressure, 
heat,  and  moisture,  to  crystalline  rock.    It  is  in  mountain  ranges  only,  where  these  conditions 
have  been  fulfilled,  and  here  are  most  of  the  valuable  deposits  of  marble. 

58.  The  choicest  varieties  of  marble  are  found  in  the  province  of  Carrara,  in  Italy. 
Black,  or  Portoro  marble,  also  comes  from  Italy.    Much  ornamental  marble  is  obtained  in 
Vermont,  Tennessee,  Maryland,  and  the  Rocky  mountains. 

59.  Rock  salt  is  found  in  nearly  every  country  in  the  world,  and  in  the  rocks  of  all 
geological  periods.   The  salt  deposits  are  usually  the  beds  of  former  lagoons,  cut  off  from  the 
sea  by  wave-formed  sand  bars. 

60.  The  salt  mines  near  Cracow  have  been  worked  for  more  than  700  years.      In  the 
United  States,  the  chief  salt  deposits  are  those  of  New  York,  Michigan,  and  Louisiana. 


WHAT  HAS  BEEN  TAUGHT  IN  CHAPTER  XX. 


Metals  and  minerals  are  closely  connected 
with  the. civilization  of  the  Jiuman  race,  and  in 
many  cases,  precede  its  tvritten  history. 

Excepting  coal,  most  of  the  metals  and  min- 
erals useful  to  man  are  found  in  highlands. 

Copper  and  iron  are  the  oldest  and  most  use- 
ful of  all  metals.  These  metals  are  extracted 
from  ores. 

Tin,  lead,  zinc,  and  quicksilver  are  of  second- 
ary importance.  Except  the  latter,  they  are 
occasionally  found  in  lowland  plains. 

Gold,  silver,  and  nickel  are  widely  but  spar- 
ingly disseminated.  They  are  usually  found  in 
veins,  ivhere  they  have  been  deposited  by  ivater. 

Sodium,  potassium,  calcium,  and  aluminium 
are  valuable  for  their  various  salts,  such  as  com- 
mon salt,  potash,  lime,  clay,  etc. 

The  diamond  is  composed  of  pure  carbon,  and 
is  the  most  highly  prized  of  gems.  It  is  found 
in  Brazil  and  South  Africa. 

The  ruby,  sapphire,  emerald,  and  topaz  are 
gems  having  aluminium  as  a  base.  TJiese  gems 
are  usually  found  in  granitic  rocks. 

Amethyst,  opal,  chalcedony,  sardonyx,  agate, 
and  jasper  are  varieties  of  quartz,  colored  with 
oxides  of  iron  or  manganese. 

The  process  of  coal  formation  consisted  of: — 
1st,  the  acccumulation  of  vegetable  matter  in 
peat  bogs  or  in  drifts  ;  2nd,  its  burial  tinder  the 
sea  ;  3rd,  its  change  to  coal  by  the  pressure  of 
overlying  sediment. 


The  principal  varieties  of  coal  are  (graphite), 
anthracite,  bituminous,  cannel,  and  lignite;  also 
the  hydrocarbons,  asphaltum,  and  petroleum. 

Tlie  coal  fields  of  the  United  States  have  an 
area  about  four  times  as  great  as  that  of  all 
of  the  other  coal  fields  in  the  world. 

Petroleum  is  derived  from  vegetable  matter, 
and  has  been  formed  in  the  presence  of  salt 
water.  The  chief  deposits  of  the  United  States 
are  found  in  Pennsylvania  and  California. 

The  principal  building  stones  are  comprised 
among  the  granitic  rocks,  sandstones,  and  lime- 
stones. 

Granite  is  found  in  nearly  all  mountain  ranges. 

Sandstone  is  formed  from  sand  cemented  into 
a  compact  mass  by  lime  or  by  oxide  of  iron.  TJie 
former  varieties  are  white  or  light  colored:  the 
latter  are  brown. 

Limestone  is  an  aqueous  rock,  and  includes 
chalk,  marble,  and  common  gray  limestone. 

Gray  limestones  are  most  abundant  in  old 
marine  plains.  TJiere  are  immense  deposits  in 
the  Mississippi  valley. 

Marble  is  a  metamorphic  limestone,  and  is 
found  usually  in  mountains,  where  the  condi- 
tions are  present  for  its  formation. 

Hock  salt  is  usually  found  in  old  lake  beds 
cut  off  from  the  sea.  Tliere  are  many  such  de- 
posits, and  they  are  found  in  all  parts  of  the 
world,  as  well  as  in  rocks  of  nearly  every  geo- 
logical age. 


Compiled  from  notes  and  maps  made  by  Major  Greely. 


RECORD     OF    RECENT    DISCOVERIES.  137 


A.  F>  P  E  1ST  13  I  X . 

THE    ORTHOGRAPHY,    BERING,    NOT    BEHRING. 

To  THE  AUTHOR  OP  MONTEITH'S  GEOGRAPHIES: — 

The  orthography,  Bering,  is  used  in  the  Coast  Survey  and  other  government  publications.  Commander  IVAN 
IVANOVTTCH  BERING  uniformly  spelled  his  name  Bering,  as  do  his  descendants  now  living  in  Denmark.  The  erroneous 
form,  Behring,  was  first  introduced  in  the  second  decade  of  the  present  century.  Special  students  of  Alaska  steadily  adhere 
to  the  correct  form,  Bering,  and  I  take  occasion  to  congratulate  you  on  the  attempt  to  spread  the  correct  form  before  a  large 
and  increasing  audience.  J.  E.  HILGARD, 

Supt.  U.  8.  Coast  and  Geodetic  Survey. 
WASHINGTON,  D.  C.,  Jan.  26,  1885. 

Lieut.  Schwatka,  an  officer  in  the  United  States  Army,  led  an  expedition  in  1879  and  1880,  in  search  of  informa- 
tion concerning  the  fate  of  Sir  John  Franklin,  a  celebrated  Arctic  explorer  who  set  out  from  England  in  1845,  to  find  a  north- 
west passage  or  commercial  route  from  that  country  to  Asia,  but  who  never  returned. 

Expeditions  had,  at  various  times,  been  sent  in  search  of  him,  but  it  was  not  until  Schwatka  accomplished  his  work  that 
all  the  members  of  the  Franklin  party  were  known  to  have  perished.  Schwatka's  is  the  longest  sledge  journey  ever  made, — 
over  3,000  miles.  His  sledges  were  drawn  by  44  dogs. 

Schwatka  met  a  native  chief  who  had  seen  either  the  Erebus  or  the  Terror,  Franklin's  ships ;  and  from  him  he  learned 
that  the  ships  were  abandoned  and  sunk,  and  that  some  spoons,  knives,  cooking  utensils,  books,  and  records  had  been  taken 
by  the  natives.  Not  knowing  the  value  or  use  of  the  books  and  records,  the  natives  gave  them  to  their  children  to  play  with. 
In  this  way,  they  were  destroyed. 

Schwatka  found  a  number  of  skeletons  of  the  Franklin  party,  which  he  buried.  This  was  on  King  William's  Land, 
southwest  of  Boothia. 

He  reports  a  temperature  in  January,  1880,  of  70°  below  zero,  and  says  his  white  men  endured  the  cold  as  well  as  the 
natives,  who  call  themselves  Inuits.  His  course  lay  northwest  from  Hudson  bay.  The  party  killed  511  reindeer. 

Lieut.  De  Long,  in  the  steam  cruiser,  Jeannette,  which  was  fitted  out  by  James  Gordon  Bennett,  entered  the  Arctic 
ocean  by  way  of  Bering  strait.  After  two  years,  in  which  the  party  suffered  greatly,  the  Jeannette  was  crushed  in  the  ice  and 
sunk  in  the  Arctic,  over  400  miles  from  the  coast  of  Siberia,  June,  1881.  Some  of  the  party,  in  an  open  boat,  entered  the 
Lena  river  and  were  rescued.  De  Long  with  a  number  of  his  men  reached  the  shore,  but  perished  from  cold  and  hunger  on 
the  frozen  wilds  of  Siberia.  Others  of  his  party  have  never  been  heard  from.  De  Long  discovered  three  small  islands,  which, 
he  named  Bennett,  Henrietta,  and  Jeannette. 

The  International  Polar  Conference  was  organized  by  the  exertions  of  the  late  Lieutenant  Karl  Wey- 
precht,  for  the  purpose  of  establishing  a  chain  of  stations  around  the  north  pole,  at  points  as  far  north  as  possible.  These 
stations  were  for  the  purpose  of  investigating  the  meteorology  of  the  north  polar  regions.  A  uniform  system  of  taking 
meteorological  pendulum,  magnetic,  tidal,  and  other  observations  was  adopted  by  the  commission. 

The  Russian  government  established  two  stations,  one  at  the  mouth  of  the  Lena  and  the  other  on  New  Siberia  island ; 
Norway,  a  station  at  Boskopen,  in  Finmark  ;  Sweden,  one  in  Spitzbergen  ;  Holland,  one  on  the  Gulf  of  Obi  ;  Denmark,  one 
at  Upernavik  ;  the  Austro-Hungarian  Monarchy,  one  at  Jan  Mayen  island  ;  and  the  United  States  two,  one  at  Point  Barrow 
and  one  at  Lady  Franklin  bay. 

The  Point  Barrow  party  reached  their  destination  in  July,  1881,  in  command  of  Lieut.  Ray,  for  many  years  in  the  U.  S. 
Signal  Service,  and  remained  in  Alaska  until  1884.  During  this  time,  a  large  number  of  observations  were  effected,  success- 
ful explorations  of  the  northwest  coast  were  undertaken,  and  many  important  discoveries  were  made  concerning  the 
topography,  zoology,  and  meteorology  of  Alaska. 

The  Lady  Franklin  bay  party  proceeded  to  a  small  established  station  at  a  place  where  a  coal-bed  had  been  discovered 
by  the  Nares  expedition.  The  party  was  in  command  of  Lieut,  (now  Brevet-Major)  Arthur  W.  Greely,  whose  twelve  years' 
service  as  meteorologist  in  the  U.  S.  Signal  Service  had  especially  qualified  him  for  such  an  undertaking.  The  party  were 
conveyed  north  of  Smith  Sound  and  landed  at  Lady  Franklin  bay  in  August,  1881.  A  station  was  established  on  the  north 
shore  of  the  bay  named  Discovery  Harbor. 

Major  Greely  explored  the  interior,  in  the  vicinity  of  Lady  Franklin  bay.  Several  large  lakes  and  mountain  ranges 
•were  surveyed.  The  highest  point  of  land  in  one  of  these,  the  United  States  Range,  was  named  Mount  Arthur. 

The  highest  temperature  recorded  was  52°  F.,  the  lowest,  — 66°  F.,  during  which  time  the  mercury  remained  frozen 
for  15  consecutive  days.1 

1  Mercury  freezes  at  —37.9". 


138 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Relief  Map  of  North  America. 


Chief  Mountain  Systems. 

ROCKY,  APPALACHIAN. 

Highest  Peaks. 


Mt.  St.  Elias 19,500  ft. 

Vol.  Popocatepetl.  .18,500  ft. 
Vol.  Orizaba 17,374  ft. 


Superior, 
Great  Bear, 


Mt.  Brown 15,900  ft. 

Mt.  Hooker 15,675  ft. 

Mt.  Whitney 15,086  ft. 

Principal  Lakes. 

Great  Slave,  Michigan,  Erie, 

Winnipeg,  Ontario,  Huron. 


Drainage  Systems. 

BASIN  OB  SLOPE.  RIVERS. 

MISSISSIPPI  BASIN Mississippi  and  tributaries. 

ST.  LAWRENCE  BASIN St.  Lawrence  and  tributaries. 

ARCTIC  SLOPE Mackenzie  and  tributaries. 

HUDSON  BAY  BASIN Nelson,  Churchill,  and  others. 

GREAT  BASIN Colorado  and  tributaries. 

PAn^rr  ST  OPF  \  Columbia.  Yukon,  San  Joaquin, 

bLOPE \      and  tributaries. 

ATLANTIC  SLOPE Numerous  short  rivers. 


RECORD     OF    RECENT    DISCOVERIES.  139 

The  displays  of  the  northern  lights  were  generally  fair,  but  not  to  be  compared  in  brilliancy  with  those  frequently 
observed  at  Disco  island,  Upernavik,  and  localities  further  south.  There  was  no  crackling  sound  accompanying  the  auroral 
display,  and,  contrary  to  expectations,  the  electrometer,  an  instrument  designed  to  show  the  presence  of  electricity,  gave  not 
the  slightest  result. 

The  highest  barometer  observed  was  31.05  inches,  and  the  lowest,  28.95  inches.  This  range,  2.1  inches,  seems  a  great 
one  for  high  latitudes,  and  shows  that  general  atmospheric  movements  are  nearly  as  great  there  as  in  the  tropics  where  they 
originate.  The  highest  velocity  of  wind  recorded  was  seventy  miles  an  hour. 

The  tidal  observations  revealed  some  startling  facts.  At  Lady  Franklin  bay,  the  tides  came  from  the  north,  but  at  Cape 
Sabine  and  Melville  Bay  the  wave  came  from  the  south.  The  water  of  the  flowing  tide  at  Discovery  Harbor  was  somewhat 
wanner  than  that  of  the  ebbing  tide.  The  average  temperature  of  the  sea  water  at  Lady  Franklin  bay  was  29°  F.,  being 
three  degrees  below  the  freezing  point  of  fresh  water. 

The  observations  in  magnetism  were  complete  and  interesting.  The  results  show  that  in  that  latitude,  the  magnetic 
needle  is  constantly  in  a  tremor,  except  during  severe  storms,  when  it  becomes  quiet.  At  Lockwood  and  Brainard's  furthest 
point  north,  the  needle  varied  104  degrees,  or  more  than  a  quarter  of  a  circle  from  the  true  meridian. 

The  furthest  point  north  reached  by  Lieut.  Lockwocd  and  Sergt.  Brainard  was  latitude  83°  24',  the  highest  ever 
attained  by  man.  Fifteen  miles  above  this  point,  a  high  promontory  was  discerned,  which  was  named  Cape  Robert  Lincoln. 
Not  only  did  Lockwood  and  Brainard  reach  the  highest  latitude,  but  they  explored  the  northern  coast  of  Greenland  150  miles 
farther  eastward  than  had  ever  before  been  trodden  by  man. 

This  party  left  Lady  Franklin  bay  in  August,  1883.  When  opposite  Cape  Sabine,  they  were  compelled  to  abandon  the 
small  steam  launch,  and  for  thirteen  days,  during  a  terrible  storm,  drifted  helplessly  on  an  ice  pack.  After  great  suffering, 
they  reached  land  and  proceeded  to  Cape  Sabine,  where  they  built  winter  quarters.  Here  they  remained  from  September, 
1883,  until  July,  1884.  Their  supply  of  food  became  exhausted,  and  the  party  suffered  horribly  during  their  encampment  at 
this  place.  All  but  nine  of  the  party  perished  from  exposure  and  starvation. 

In  the  meantime,  Commander  Schley  had  been  ordered  to  proceed  in  search  of  the  party,  and  with  three  steam  vessels, 
the  Thetis,  Bear,  and  Alert,  he  reached  Cape  Sabine,  in  eighteen  days  from  time  of  leaving  Upernavik — a  feat  unparalleled  in 
the  annals  of  Arctic  exploration. 

The  results  attained  by  the  observations  of  Major  Greely  and  Lieut.  Ray  hr.ve  given  the  world  more  knowledge  con- 
cerning the  meteorology  of  the  polar  regions  than  those  of  all  other  expeditions  combined.  This  is  due,  not  only  to  the 
thorough  training  of  the  officers  and  men  in  charge,  but  also  to  the  system  and  skill  with  which  the  observations  were  taken 
and  their  mutual  relations  considered. 

Ocean  Hydrography. — The  surveys  made  by  the  Coast  Survey  Steamer  Blake  in  the  Gulf  of  Mexico  and  along 
the  eastern  coast  of  the  United  States,  have  established  a  number  of  facts  quite  contrary  to  those  hitherto  asserted. 

The  contour  of  the  bed  of  the  gulf  reveals  the  existence  of  a  succession  of  terraces  or  steps,  of  uniform  width  and 
depth,  extending  around  the  gulf  somewhat  like  the  rows  of  seats  in  an  amphitheater.  The  first  of  these  terraces  varies 
from  thirty  to  one  hundred  miles  in  width,  on  which  the  depth  of  water  is  less  than  500  feet.  Then  the  bottom  slopes  quite 
abruptly  to  the  next  terrace,  on  which  the  water  has  an  average  depth  of  2,500  feet.  This  terrace  is  a  narrow  one,  not  more 
than  twenty  or  thirty  miles  wide.  The  slope  to  the  next  terrace  is  likewise  quite  steep,  on  which  the  average  depth  of  water 
is  about  4,000  feet.  The  descent  to  the  next  terrace  is  still  more' abrupt,  and  the  depth  of  water  thereon  is  about  10,000  feet. 
This  terrace  is  about  one  hundred  miles  wide  and  tolerably  uniform  in  width.  The  lowest  part  of  the  bed  is  in  the  center  of 
the  gulf,  and  the  water  here  has  a  depth  of  about  12,000  feet.  The  deepest  sounding  reached  is  2,119  fathoms,  or  12,714  feet. 

Between  Florida  and  Yucatan,  is  a  submarine  ridge  on  which  the  depth  of  water  nowhere  exceeds  6,000  feet.  From  the 
lowest  summit  of  this  ridge,  the  island  of  Cuba  rises  with  almost  precipitous  walls.  Within  five  miles  of  either  of  the  Cuban 
shores,  the  depth  of  water  is  nearly  6,000  feet,  while  the  slopes  towards  Yucatan  and  Florida  are  uniform  and  gentle.  On  these 
ridges,  the  temperature  of  the  water  obeys  the  law  of  temperature,  decreasing  uniformly  to  the  bottom.  Within  the  gulf,  this 
is  not  the  case.  Here  the  temperature  decreases  until  the  depth  of  water  on  the  ridge  is  reached,  below  which  the  tempera- 
ture is  uniform.  That  is,  no  colder  water  enters  the  gulf  than  that  which  is  found  on  the  ridge. 

The  movements  of  water  within  the  gulf  are  found  to  be  irregular,  and  governed  to  a  great  extent  by  the  wind.  Along 
the  northern  shores,  there  is  generally  an  eastward  drift  of  water  caused  by  the  prevailing  winds.  At  times,  this  drift  is  not 
only  arrested,  but  occasionally  reversed.  The  surveys  of  Commander  Bartlett  show  conclusively  that  not  only  has  the  drift 
of  the  gulf  no  connection  with  the  Gulf  Stream,  but  also  that  the  waters  of  the  Gulf  Stream  do  not  enter  the  Gulf  of  Mexico. 
On  the  contrary,  no  water  of  the  Gulf  Stream  passes  further  west  than  Florida  strait. 

Commander  Bartlett's  surveys  along  the  eastern  coast  of  Florida  also  demonstrate  that  the  Gulf  Stream,  instead 
of  flowing  upon  a  bed  of  cold  water — an  opinion  which  has  obtained  for  many  years — really  extends  to  the  bottom,  and  in 
many  places,  flows  with  a  velocity  sufficient  to  sweep  it  bare  of  ooze.  In  most  localities,  the  bottom  is  strewn  with  minute 
shells  brought  from  the  Caribbean  sea.  In  the  vicinity  of  Hatteras  inlet  the  bottom  is  covered  with  shells  or  skeletons 
of  organisms  brought  by  the  Arctic  current,  which,  at  this  locality,  is  an  undercurrent.  Opposite  Charleston,  there  is  » 


140 


RELIEF     MAPS. 


Relief  Map  of  Asia 


Chief  Mountain  Systems. 

HIMALAYA,  STANOVOY. 

Highest  Peaks. 


Mt.  Everest 29,000  ft. 

Mt.  Kunchinginga.,28,178  ft. 
Mt.  Dhawala-giri,.  .28,000  ft. 


Caspian, 
Balcash, 


Mt.  Choumalarie. .  .23,929  ft. 

Mt.  Ararat 17,210ft. 

Mt.  Sinai 7,497ft. 

Lakes  and  Inland  Seas. 

Aral,  Dead,  Baikal, 

Bouka,  Lop,  Koko. 


Drainage  Systems. 

BASIN  OK  SLOPE.  RIVERS. 

j  Obi,    Yenisei, 


ARCTIC  SLOPE.. 


STOPP  Unioor, 

bLOPE  ..............  \     and 


others. 

Hoang, 
others. 


Lena,    and 
Yang-tse, 


(Indus,    Ganges,  Irrawaddy 
INDIAN  SLOPE  ...............  j     and'  Cam&dia. 

CENTRAL  STEPPE  REGIONS  ......  Cashgar  and  others. 

SYRIAN  BASIN  .................  Tigris,  Euphrates. 


RECORD     OF    RECENT    DISCOVERIES.  141 

strong  and  well-known  surface  current  from  the  north,  to  which  the  name  of  "  Little  Hell "  is  given  on  the  piloi  charts. 
After  flowing  on  the  surface  for  about  one  hundred  miles,  it  disappears.  This  phenomenon  is  believed  by  Commander  Bartlett 
to  be  due  to  the  rising  of  the  Arctic  current  to  the  surface. 

Dr.  W.  H.  Dall,  of  the  Coast  Survey,  on  investigating  the  currents  of  Bering  sea,  has  likewise  shown  that  many 
of  the  popular  opinions  concerning  them  are  erroneous.  The  opinion  has  hitherto  prevailed  that  the  Kuro  Siwo,  or  Japan 
Current,  forked  near  the  southern  extremity  of  Kamtschatka,  the  main  branch  being  deflected  to  the  western  coast  of  North 
America,  while  a  smaller  branch  passed  through  Bering  strait,  where  "its  benign  influence  is  felt  in  tempering  the  north- 
western coast."  After  three  years  of  observations,  conducted  under  the  most  favorable  circumstances,  Dall  finds  that  no 
current  of  water  enters  the  Arctic  ocean  through  Bering  strait,  and  that  the  only  current  manifest,  is  a  feeble,  cold  current 
from  the  Arctic  ocean.  Nortli  of  the  strait,  the  only  movements  are  drifts  which  are  caused  by  the  winds.  The  prevailing 
•direction  of  the  drift  is  to  the  west  or  northwest,  as  was  illustrated  by  the  Jeannette,  which,  nipped  by  the  ice  near  Herald 
island,  was  carried  to  a  point  nearly  opposite  the  mouth  of  the  Lena  river. 

Physiography  of  Greenland. — Prof.  Nordenskjold,  already  famous  for  various  and  successful  Arctic  explora- 
tions, has  recently  penetrated  the  interior  of  Greenland  to  a  distance  of  about  100  miles,  greatly  increasing  our  limited 
knowledge  of  that  island.  Up  to  the  time  of  Nordenskj old's  expedition,  it  had  been  believed  by  many  that  a  large  and 
fertile  plateau  covered  with  vegetation  existed  in  the  interior  of  Greenland. 

It  has  been  long  known  that  nine  centuries  ago,1  Norwegian  navigators  were  well  acquainted  with  the  coast  of  Green- 
land and  that  flourishing  colonies  were  planted  there.  Two  hundred  years  afterward,  the  connection  of  these  colonies  with 
the  mother  country  was  severed.  Since  that  time,  the  fate  of  the  colonists  is  unknown.  Whether  they  had  been  exter- 
minated by  the  Esquimaux,  or  absorbed  by  them,  or  whether  climatic  changes  fatal  to  the  colonists  had  taken  place,  were 
•questions  that  Nordenskjold  determined  to  learn  by  a  visit  to  the  interior. 

Two  days  after  leaving  Reikiavik,  Iceland,  the  eastern  shores  of  Greenland  were  seen.  After  steaming  along  the 
•coast  for  several  days,  unsuccessful  in  finding  a  place  for  landing,  the  Sophia  was  headed  for  Disco  bay  on  the  western  coast. 
Here,  Nordenskjold  with  his  sledge  party  landed,  and  arranged  the  details  of  the  expedition.  Nine  sturdy  Lapps  were  selected, 
sledges  were  constructed,  and  the  necessary  apparatus  for  scientific  observations  were  put  in  order  for  use. 

The  expedition  proceeded  in  a  boat  up  a  small  stream  flowing  into  Disco  bay.  After  four  days,  the  boat  was  abandoned 
and  the  sledge  journey  begun.  The  ice  was  so  furrowed  by  crevasses  that  it  was  impossible,  at  times,  to  advance  more  than 
three  or  four  miles  a  day.  After  reaching  a  distance  of  about  100  miles  inland,  Nordenskjold  sent  a  party  of  Lapps  ahead 
-about  70  miles.  They  made  the  trip  on  skidors,  or  snow  shoes  resembling  sled  runners,  requiring  but  57  hours  for  the 
•whole  distance.  During  this  time  they  slept  but  four  hours.  At  this  distance,  there  was  no  sign  of  land  ;  nothing  could 
be  seen  but  snow  and  ice.  The  height,  as  recorded  by  aneroid  barometers,  was  a  little  less  than  7,000  feet,  and  the  altitude 
•was  still  increasing  towards  the  east. 

During  the  entire  trip,  but  few  signs  of  life  were  visible.  A  small  worm  which  lives  on  ice  algce,  and  a  few  birds 
only,  were  observed.  The  birds,  with  the  exception  of  two  ravens,  were  water  fowl.  The  latter  were  returning  from  the 
north.  The  only  vegetation  observed  consisted  of  the  various  species  of  algae,  which  give  their  peculiar  color  to  the  snow. 
These  are,  in  most  cases,  microscopic  in  size,  and  are  the  cause  of  the  red  appearance  of  the  snow  occasionally  observed  in 
high  latitudes. 

One  of  the  most  interesting  features  noticed  was  the  existence  of  a  peculiar  "  dust,"  or  finely-divided  mineral  sub- 
stance, which  seemed  to  cover  the  whole  interior  of  the  island.  From  the  manner  in  which  it  is  distributed,  it  is  impossible 
that  it  should  be  native  to  the  island.  On  the  top  of  snow,  which  was  still  soft,  the  dust  was  evenly  deposited.  Wherever 
the  temperature  was  above  the  melting  point,  the  dust  had  melted  it  away  just  beneath  the  surface.  Along  the  glaciers,  the 
water  had  frequently  collected  large  quantities  of  it  in  pools.  The  chemical  composition  of  this  substance  closely  resembles 
that  of  meteorites,  and  contains  a  large  percentage  of  metallic  iron  and  nickel.  The  dust  was  entirely  free  from  sand  or  mud 
of  sedimentary  origin,  and  was  without  doubt  deposited  there  through  the  agency  of  the  winds.  Nordenskjold  has  given  it 
the  name  of  Kryokonite. 

After  returning  to  the  coast,  the  expedition  re-embarked  on  the  Sophia  and  again  proceeded  to  the  eastern  coast  of  the 
island.  This  time,  Nordenskjold  succeeded  in  effecting  a  landing — the  first  made  south  of  the  Arctic  circle,  for  several  cen- 
turies. Here  were  discovered  a  few  ancient  ruins,  the  only  traces  of  the  former  settlements  seen  during  the  expedition. 

During  the  voyage  along  the  coast,  soundings  and  dredgings  were  made  on  all  possible  occasions.  A  large  number  of 
temperature  measurements,  made  with  the  most  approved  apparatus,  "  demonstrate  that  the  cold  current  running  along  the 
east  coast  is,  both  in  width  and  depth,  very  insignificant,  and  rests  even  near  the  shore  upon  a  current  of  warm  water  pro- 
duced by  the  Gulf  Stream.  Davis  Sound  and  Baffin  Bay,  on  the  other  hand,  are  filled  with  cold  or  very  slightly  wanned  water 
w  me  bottom.  Contrary,  therefore,  to  the  general  belief,  the  west  coast  of  Greenland  is  washed  by  cold  water,  while  a  greatly 
heated  current  coming  from  the  south  runs  along  the  east  coast  a  distance  of  only  40  or  50  miles  from  the  shore," 

1  Greenland  was  discovered  by  Erik  Rode  before  the  year  1000. 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Relief  Map  of  Europe. 


Chief  Mountain  System. 

ALPINE. 

Secondary  Systems. 

Scandinavian,  Ural. 


Cantabrian, 
Carpathian, 
Balkan', 


Other  Ranges. 

Apennines, 
Cau'casus, 
Pindus. 

Highest  Peaks. 


Valdai  Hills, 
Sierra  Nevada, 


Mt  Elboorz 17,796  ft. 

fci  Blanc 15,810  ft. 

Mt.  Kosa 15,208  ft. 


Mt.  Cervin 14,771  ft. 

Mt.  Pelvoux .14,108  ft, 

Finister  Aarhorn. .  .14,026  ft. 


Drainage  Systems. 

BASIN  OB  SLOPE.  RIVERS. 

(Don.  Dnieper,  Danube,  and 
BLACK  SEA  BASIN  ............  -j     ot^erg    * 

CASPIAN  SEA  BASIN  ............  Volga,  Ural,  and  others. 


MEDITERKANEAN  SEA  BASIN  ____  Rhone,  Ebro,  Po,  Tiber. 
ARCTIC  SLOPE  ..................  Petchora,  Dwina,  Mezene. 

~,  (  Seine,  Douro,  Loire,  TaffJ 

ATLANTIC  SLOPE  .............  -j     Garonne>  Guadiana. 

Lakes. 

Lad'oga,  Onega,  Geneva,  Como,. 

Elton,  Wener,  Wetter. 


RELIEF     MAPS, 


143 


Relief  Map  of  South  America. 


Chief  Mountain  Systems. 
ANDEAN,  BRAZILIAN. 

Highest  Peaks. 


Mt.  Aconcagua 23,900  ft. 

Mt.  Sahama 22,350  ft. 

Vol.  Qualatieri 22,000  ft. 


Mt.  Chimborazo 21,424  ft. 

Mt.  Sorata 21,286  ft. 

Mt.  IlHmani 21,149ft. 


Lakes. 


Maracaybo 


Titicaca. 


Drainage  Systems. 

BASIN  OB  SLOPE.  RIYEBS. 

ORINOCO  BASIN  OR  VALLEY Orinoco  and  tributaries. 

TT  (Amazon.     Tocantins,     and 

AMAZON  VALLEY -j     tribut;ries. 

N.  E.  ATLANTIC  SLOPE San  Francisco  and  others. 

LA  PLATA  VALLEY La  Plata  and  tributaries. 

S.  E.  ATLANTIC  SLOPE Colorado,  Nero,  and  others. 

PACIFIC  SLOPE.  . .  .  .Numerous  short  rivers. 


144 


MONTEITH'S    NEW    PHYSICAL     GEOGRAPHY. 


Belief  Map  of  Africa. 


Chief  Mountain  Systems. 

CHAIN  ALONG  E.  COAST  (no  name).  KONG. 

Highest  Peaks. 


Kenia  (E.  Africa).  .  .20,000  ft. 
Kilima  Njaro  "  ...  18.500  ft. 
Gambaragara(C.Al)  18,500  ft. 


Victoria, 
Lincoln  (?), 


Albert, 
Moero, 


Abba  Jared  (Abys'ia)  15,000  ft. 
Teneriffe  (N.W.  Afr.)  12,182  ft. 
Miltsin  (Morocco)...  .11,400  ft. 
Lakes. 

Tanganyika,  Nyassa, 

Bangweolo,  Tchad. 


Drainage  System. 

BASIN  OB  SLOPB.  RIVERS. 

NILE  BASIN Nile  and  tributaries. 

CENTRAL  BASIN Congo  and  tributaries. 

NORTH  ATLANTIC  SLOPE Senegal  and  others. 

NIGER  BASIN Niger  and  tributaries. 

SOUTH  CENTRAL  BASIN Zambeze  and  tributaries. 

INDIAN  SLOPE Numerous  short  rivers. 

NORTH  CENTRAL  STEPPE Several  short  rivers. 


RETURN  TO  the  circulation  desk  of  any 
University  of  California  Library 

or  to  the 

NORTHERN  REGIONAL  LIBRARY  FACILITY 
Bldg.  400,  Richmond  Field  Station 
University  of  California 
Richmond,  CA  94804-4698 

ALL  BOOKS  MAY  BE  RECALLED  AFTER  7  DAYS 

•  2-month  loans  may  be  renewed  by  calling 
(510)642-6753 

•  1-year  loans  may  be  recharged  by  bringing 
books  to  NRLF 

•  Renewals  and  recharges  may  be  made  4 
days  prior  to  due  date. 


DUE  AS  STAMPED  BELOW 


JAN  01  200! 


YE  00712 


